HTML5

<h1><img alt="The Breakfast Combo"
         src="banner.jpeg"
         srcset="banner-HD.jpeg 2x, banner-phone.jpeg 100w, banner-phone-HD.jpeg 100w 2x"></h1>

---

An img is always in one of the following states:

Unavailable

The user agent hasn't obtained any image data.

Partially available

The user agent has obtained some of the image data.

Completely available

The user agent has obtained all of the image data.

Broken

The user agent has obtained all of the image data that it can, but it cannot decode the image (e.g. the image is corrupted, or the format is not supported, or no data could be obtained).

When an img element is either in the partially available state or in the completely available state, it is said to be available.

An img element is initially unavailable.

When an img element is available, it provides a paint source whose width is the image's intrinsic width, whose height is the image's intrinsic height, and whose appearance is the intrinsic appearance of the image.

User agents may obtain images immediately or on demand.

A user agent that obtains images immediately must synchronously update the image data of an img element whenever that element is created with a src attribute, a srcset attribute, or both. A user agent that obtains images immediately must also synchronously update the image data of an img element whenever that element has its src, srcset, or crossorigin attribute set, changed, or removed.

A user agent that obtains images on demand must update the image data of an img element whenever it needs the image data (i.e. on demand), but only if the img element has a src or srcset attribute, and only if the img element is in the unavailable state. When an img element's src, srcset, or crossorigin attribute set, changed, or removed, if the user agent only obtains images on demand, the img element must return to the unavailable state.

Each img element has a last selected source, which must initially be null, and a current pixel density, which must initially be undefined.

When an img element has a current pixel density that is not 1.0, the element's image data must be treated as if its resolution, in device pixels per CSS pixels, was the current pixel density.

For example, if the current pixel density is 3.125, that means that there are 300 device pixels per CSS inch, and thus if the image data is 300x600, it has an intrinsic dimension of 96 CSS pixels by 192 CSS pixels.

Each Document object must have a list of available images. Each image in this list is identified by a tuple consisting of an absolute URL, a CORS settings attribute mode, and, if the mode is not No CORS, an origin. User agents may copy entries from one Document object's list of available images to another at any time (e.g. when the Document is created, user agents can add to it all the images that are loaded in other Documents), but must not change the keys of entries copied in this way when doing so. User agents may also remove images from such lists at any time (e.g. to save memory).

When the user agent is to update the image data of an img element, it must run the following steps:

1. Return the img element to the unavailable state.

2. If an instance of the fetching algorithm is still running for this element, then abort that algorithm, discarding any pending tasks generated by that algorithm.

3. Forget the img element's current image data, if any.

4. If the user agent cannot support images, or its support for images has been disabled, then abort these steps.

5. If the element has a srcset attribute specified, then let selected source and selected pixel density be the URL and pixel density that results from processing the image candidates, respectively. Otherwise, if the element has a src attribute specified and its value is not the empty string, let selected source be the value of the element's src attribute, and selected pixel density be 1.0. Otherwise, let selected source be null and selected pixel density be undefined.

6. Let the img element's last selected source be selected source and the img element's current pixel density be selected pixel density.

7. Resolve selected source, relative to the element. If that is not successful, abort these steps.

8. Let key be a tuple consisting of the resulting absolute URL, the img element's crossorigin attribute's mode, and, if that mode is not No CORS, the Document object's origin.

9. If the list of available images, contains an entry for key, then set the img element to the completely available state, update the presentation of the image appropriately, queue a task to fire a simple event named load at the img element, and abort these steps.

10. Asynchronously await a stable state, allowing the task that invoked this algorithm to continue. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)

11. ⌛ If another instance of this algorithm for this img element was started after this instance (even if it aborted and is no longer running), then abort these steps.

    Only the last instance takes effect, to avoid multiple requests when, for example, the src, srcset, and crossorigin attributes are all set in succession.

12. ⌛ If selected source is null, then set the element to the broken state, queue a task to fire a simple event named error at the img element, and abort these steps.

13. Do a potentially CORS-enabled fetch of the absolute URL that resulted from the earlier step, with the mode being the state of the element's crossorigin content attribute, the origin being the origin of the img element's Document, and the default origin behaviour set to taint.

    The resource obtained in this fashion, if any, is the img element's image data. It can be either CORS-same-origin or CORS-cross-origin; this affects the origin of the image itself (e.g. when used on a canvas).

    Fetching the image must delay the load event of the element's document until the task that is queued by the networking task source once the resource has been fetched (defined below) has been run.

    This, unfortunately, can be used to perform a rudimentary port scan of the user's local network (especially in conjunction with scripting, though scripting isn't actually necessary to carry out such an attack). User agents may implement cross-origin access control policies that are stricter than those described above to mitigate this attack, but unfortunately such policies are typically not compatible with existing Web content.

    The first task that is queued by the networking task source while the image is being fetched must set the img element's state to partially available.

    If the resource is in a supported image format, then each task that is queued by the networking task source while the image is being fetched must update the presentation of the image appropriately (e.g. if the image is a progressive JPEG, each packet can improve the resolution of the image); furthermore, the last task that is queued by the networking task source once the resource has been fetched must act as appropriate given the following alternatives:

    If the download was successful

    Set the img element to the completely available state, update the presentation of the image appropriately, add the image to the list of available images using the key key, and fire a simple event named load at the img element.

    Otherwise

    Set the img element to the broken state, and fire a simple event named error at the img element.

    On the other hand, if the resource type is multipart/x-mixed-replace, then each task that is queued by the networking task source while the image is being fetched must also update the presentation of the image, but as each new body part comes in, it must replace the previous image. Once one body part has been completely decoded, the user agent must set the img element to the completely available state and queue a task to fire a simple event named load at the img element.

    If at any point the user agent discovers that the image data is corrupted in some fatal way, or that the image data is not in a supported file format, then the user agent must set the img element to the broken state. If the fetching algorithm is still running for this element, then the user agent must also abort that algorithm, discarding any pending tasks generated by that algorithm, and then queue a task to fire a simple event named error at the img element.

While a user agent is running the above algorithm for an element x, there must be a strong reference from the element's Document to the element x, even if that element is not in its Document.

When an img element is in the completely available state and the user agent can decode the media data without errors, then the img element is said to be fully decodable.

Whether the image is fetched successfully or not (e.g. whether the response code was a 2xx code or equivalent) must be ignored when determining the image's type and whether it is a valid image.

This allows servers to return images with error responses, and have them displayed.

The user agents should apply the image sniffing rules to determine the type of the image, with the image's associated Content-Type headers giving the official type. If these rules are not applied, then the type of the image must be the type given by the image's associated Content-Type headers.

User agents must not support non-image resources with the img element (e.g. XML files whose root element is an HTML element). User agents must not run executable code (e.g. scripts) embedded in the image resource. User agents must only display the first page of a multipage resource (e.g. a PDF file). User agents must not allow the resource to act in an interactive fashion, but should honor any animation in the resource.

This specification does not specify which image types are to be supported.

---

When the user agent is required to process the image candidates of an img element's srcset attribute, the user agent must run the following steps, which return a URL and pixel density (null and undefined respectively if no selection can be made):

1. Let input be the value of the img element's srcset attribute.

2. Let position be a pointer into input, initially pointing at the start of the string.

3. Let raw candidates be an initially empty ordered list of URLs with associated unparsed descriptors. The order of entries in the list is the order in which entries are added to the list.

4. Splitting loop: Skip whitespace.

5. Collect a sequence of characters that are not space characters, and let that be url.

6. If url is empty, then jump to the step labeled descriptor parser.

7. Collect a sequence of characters that are not U+002C COMMA characters (,), and let that be descriptors.

8. Add url to raw candidates, associated with descriptors.

9. If position is past the end of input, then jump to the step labeled descriptor parser.

10. Advance position to the next character in input (skipping past the U+002C COMMA character (,) separating this candidate from the next).

11. Return to the step labeled splitting loop.

12. Descriptor parser: Let candidates be an initially empty ordered list of URLs each with an associated pixel density, and optionally an associated width and/or height. The order of entries in the list is the order in which entries are added to the list.

13. For each entry in raw candidates with URL url associated with the unparsed descriptors unparsed descriptors, in the order they were originally added to the list, run these substeps:

    1. Let descriptor list be the result of splitting unparsed descriptors on spaces.

    2. Let error be no.

    3. Let width be absent.

    4. Let height be absent.

    5. Let density be absent.

    6. For each token in descriptor list, run the appropriate set of steps from the following list:

       If the token consists of a valid non-negative integer followed by a U+0077 LATIN SMALL LETTER W character

       1. If width is not absent, then let error be yes.

       2. Apply the rules for parsing non-negative integers to the token. Let width be the result.

       If the token consists of a valid non-negative integer followed by a U+0068 LATIN SMALL LETTER H character

       1. If height is not absent, then let error be yes.

       2. Apply the rules for parsing non-negative integers to the token. Let height be the result.

       If the token consists of a valid floating-point number followed by a U+0078 LATIN SMALL LETTER X character

       1. If density is not absent, then let error be yes.

       2. Apply the rules for parsing floating-point number values to the token. Let density be the result.

    7. If width is still absent, set it to Infinity.

    8. If height is still absent, set it to Infinity.

    9. If density is still absent, set it to 1.0.

    10. If error is still no, then add an entry to candidates whose URL is url, associated with a width width, a height height, and a pixel density density.

14. If the img element has a src attribute whose value is not the empty string, then run the following substeps:

    1. Let url be the value of the element's src attribute.

    2. Add an entry to candidates whose URL is url, associated with a width Infinity, a height Infinity, and a pixel density 1.0.

15. If candidates is empty, return null and undefined and abort these steps.

16. If an entry b in candidates has the same associated width, height, and pixel density as an earlier entry a in candidates, then remove entry b. Repeat this step until none of the entries in candidates have the same associated width, height, and pixel density as an earlier entry.

17. Optionally, return the URL of an entry in candidates chosen by the user agent, and that entry's associated pixel density, and then abort these steps. The user agent may apply any algorithm or heuristic in its selection of an entry for the purposes of this step.

    This allows a user agent to override the default algorithm (as described in subsequent steps) in case the user agent has a reason to do so. For example, it would allow the user agent in highly bandwidth-constrained conditions to intentionally opt to use an image intended for a smaller screen size, on the assumption that it'll probably be good enough. Implementors are urged to avoid doing this if at all possible, to let authors have predictable results. The results of using an image intended for a different viewport size can be, at a minimum, aesthetically displeasing.

    This clause is not necessary to select images that are of lower pixel density than the display can handle, because the definition of pixel density below is also left up to the user agent. This step is only needed to allow user agents to pick images intended for viewports with other dimensions.

18. Let max width be the width of the viewport, and let max height be the height of the viewport. [CSS]

19. If there are any entries in candidates that have an associated width that is less than max width, then remove them, unless that would remove all the entries, in which case remove only the entries whose associated width is less than the greatest such width.

20. If there are any entries in candidates that have an associated height that is less than max height, then remove them, unless that would remove all the entries, in which case remove only the entries whose associated height is less than the greatest such height.

21. If there are any entries in candidates that have an associated pixel density that is less than a user-agent-defined value giving the nominal pixel density of the display, then remove them, unless that would remove all the entries, in which case remove only the entries whose associated pixel density is less than the greatest such pixel density.

22. Remove all the entries in candidates that have an associated width that is greater than the smallest such width.

23. Remove all the entries in candidates that have an associated height that is greater than the smallest such height.

24. Remove all the entries in candidates that have an associated pixel density that is greater than the smallest such pixel density.

25. Return the URL of the sole remaining entry in candidates, and that entry's associated pixel density.

The user agent may at any time run the following algorithm to update an img element's image in order to react to changes in the environment. (User agents are not required to ever run this algorithm.)

1. Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)

2. ⌛ If the img element does not have a srcset attribute specified, is not in the completely available state, has image data whose resource type is multipart/x-mixed-replace, or if its update the image data algorithm is running, then abort this algorithm.

3. ⌛ Let selected source and selected pixel density be the URL and pixel density that results from processing the image candidates, respectively.

4. ⌛ If selected source is null, then abort these steps.

5. ⌛ If selected source and selected pixel density are the same as the element's last selected source and current pixel density, then abort these steps.

6. ⌛ Resolve selected source, relative to the element.

7. ⌛ Let CORS mode be the state of the element's crossorigin content attribute.

8. ⌛ If the resolve a URL algorithm is not successful, abort these steps.

9. End the synchronous section, continuing the remaining steps asynchronously.

10. Do a potentially CORS-enabled fetch of the resulting absolute URL, with the mode being CORS mode, the origin being the origin of the img element's Document, and the default origin behaviour set to taint.

    If this download fails in any way (other than the response code not being a 2xx code, as mentioned earlier), or if the image format is unsupported (as determined by applying the image sniffing rules, again as mentioned earlier), or if the resource type is multipart/x-mixed-replace, then abort these steps.

    Otherwise, wait for the fetch algorithm to queue its last task, and then continue with these steps. The data obtained in this way is used in the steps below.

11. Queue a task to run the following substeps:

    1. If the img element's src, srcset, or crossorigin attributes have been set, changed, or removed since this algorithm started, then abort these steps.

    2. Let the img element's last selected source be selected source and the img element's current pixel density be selected pixel density.

    3. Replace the img element's image data with the resource obtained by the earlier step of this algorithm. It can be either CORS-same-origin or CORS-cross-origin; this affects the origin of the image itself (e.g. when used on a canvas).

    4. Fire a simple event named load at the img element.

---

The task source for the tasks queued by algorithms in this section is the DOM manipulation task source.

---

What an img element represents depends on the src attribute and the alt attribute.

If the src attribute is set and the alt attribute is set to the empty string

The image is either decorative or supplemental to the rest of the content, redundant with some other information in the document.

If the image is available and the user agent is configured to display that image, then the element represents the element's image data.

Otherwise, the element represents nothing, and may be omitted completely from the rendering. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.

If the src attribute is set and the alt attribute is set to a value that isn't empty

The image is a key part of the content; the alt attribute gives a textual equivalent or replacement for the image.

If the image is available and the user agent is configured to display that image, then the element represents the element's image data.

Otherwise, the element represents the text given by the alt attribute. User agents may provide the user with a notification that an image is present but has been omitted from the rendering.

If the src attribute is set and the alt attribute is not

The image might be a key part of the content, and there is no textual equivalent of the image available.

In a conforming document, the absence of the alt attribute indicates that the image is a key part of the content but that a textual replacement for the image was not available when the image was generated.

If the image is available and the user agent is configured to display that image, then the element represents the element's image data.

Otherwise, the user agent should display some sort of indicator that there is an image that is not being rendered, and may, if requested by the user, or if so configured, or when required to provide contextual information in response to navigation, provide caption information for the image, derived as follows:

1. If the image has a title attribute whose value is not the empty string, then the value of that attribute is the caption information; abort these steps.

2. If the image is a descendant of a figure element that has a child figcaption element, and, ignoring the figcaption element and its descendants, the figure element has no Text node descendants other than inter-element whitespace, and no embedded content descendant other than the img element, then the contents of the first such figcaption element are the caption information; abort these steps.

If the src attribute is not set and either the alt attribute is set to the empty string or the alt attribute is not set at all

The element represents nothing.

Otherwise

The element represents the text given by the alt attribute.

The alt attribute does not represent advisory information. User agents must not present the contents of the alt attribute in the same way as content of the title attribute.

User agents may always provide the user with the option to display any image, or to prevent any image from being displayed. User agents may also apply heuristics to help the user make use of the image when the user is unable to see it, e.g. due to a visual disability or because they are using a text terminal with no graphics capabilities. Such heuristics could include, for instance, optical character recognition (OCR) of text found within the image.

While user agents are encouraged to repair cases of missing alt attributes, authors must not rely on such behavior. Requirements for providing text to act as an alternative for images are described in detail below.

The contents of img elements, if any, are ignored for the purposes of rendering.

The alt, src, and srcset IDL attributes must reflect the respective content attributes of the same name.

The crossOrigin IDL attribute must reflect the crossorigin content attribute.

The useMap IDL attribute must reflect the usemap content attribute.

The isMap IDL attribute must reflect the ismap content attribute.

The IDL attributes width and height must return the rendered width and height of the image, in CSS pixels, if the image is being rendered, and is being rendered to a visual medium; or else the intrinsic width and height of the image, in CSS pixels, if the image is available but not being rendered to a visual medium; or else 0, if the image is not available. [CSS]

On setting, they must act as if they reflected the respective content attributes of the same name.

The IDL attributes naturalWidth and naturalHeight must return the intrinsic width and height of the image, in CSS pixels, if the image is available, or else 0. [CSS]

The IDL attribute complete must return true if any of the following conditions is true:

• The src attribute is omitted.
• The src attribute's value is the empty string.
• The final task that is queued by the networking task source once the resource has been fetched has been queued, but has not yet been run, and the img element is not in the broken state.
• The img element is completely available.

Otherwise, the attribute must return false.

The value of complete can thus change while a script is executing.

Three constructors are provided for creating HTMLImageElement objects (in addition to the factory methods from DOM Core such as createElement()): Image(), Image(width), and Image(width, height). When invoked as constructors, these must return a new HTMLImageElement object (a new img element). If the width argument is present, the new object's width content attribute must be set to width. If the height argument is also present, the new object's height content attribute must be set to height. The element's document must be the active document of the browsing context of the Window object on which the interface object of the invoked constructor is found.

<p>I lived in <img src="carouge.svg" alt=""> Carouge.</p>

<p>Home town: <img src="carouge.svg" alt="Carouge"></p>

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt="The coat of arms depicts a lion, sitting in front of a tree."></p>
<p>It is used as decoration all over the town.</p>

<p>Carouge has a coat of arms.</p>
<p><img src="carouge.svg" alt=""></p>
<p>The coat of arms depicts a lion, sitting in front of a tree.
It is used as decoration all over the town.</p>

<p>He picked up the folder and a piece of paper fell out.</p>
<p><img src="carouge.svg" alt="Shaped like a shield, the paper had a
red background, a green tree, and a yellow lion with its tongue
hanging out and whose tail was shaped like an S."></p>
<p>He stared at the folder. S! The answer he had been looking for all
this time was simply the letter S! How had he not seen that before? It all
came together now. The phone call where Hector had referred to a lion's tail,
the time Marco had stuck his tongue out...</p>

<p>The last user to have uploaded a coat of arms uploaded this one:</p>
<p><img src="last-uploaded-coat-of-arms.cgi" title="User-uploaded coat of arms."></p>

<article>
 <h1>My cats</h1>
 <h2>Fluffy</h2>
 <p>Fluffy is my favorite.</p>
 <img src="fluffy.jpg" alt="She likes playing with a ball of yarn.">
 <p>She's just too cute.</p>
 <h2>Miles</h2>
 <p>My other cat, Miles just eats and sleeps.</p>
</article>

<article>
 <h1>Photography</h1>
 <h2>Shooting moving targets indoors</h2>
 <p>The trick here is to know how to anticipate; to know at what speed and
 what distance the subject will pass by.</p>
 <img src="fluffy.jpg" alt="A cat flying by, chasing a ball of yarn, can be
 photographed quite nicely using this technique.">
 <h2>Nature by night</h2>
 <p>To achieve this, you'll need either an extremely sensitive film, or
 immense flash lights.</p>
</article>

<article>
 <h1>About me</h1>
 <h2>My pets</h2>
 <p>I've got a cat named Fluffy and a dog named Miles.</p>
 <img src="fluffy.jpg" alt="Fluffy, my cat, tends to keep itself busy.">
 <p>My dog Miles and I like go on long walks together.</p>
 <h2>music</h2>
 <p>After our walks, having emptied my mind, I like listening to Bach.</p>
</article>

<article>
 <h1>Fluffy and the Yarn</h1>
 <p>Fluffy was a cat who liked to play with yarn. He also liked to jump.</p>
 <aside><img src="fluffy.jpg" alt="" title="Fluffy"></aside>
 <p>He would play in the morning, he would play in the evening.</p>
</article>

<h1>Pick your color</h1>
<ul>
 <li><a href="green.html"><img src="green.jpeg" alt="Green"></a></li>
 <li><a href="blue.html"><img src="blue.jpeg" alt="Blue"></a></li>
 <li><a href="red.html"><img src="red.jpeg" alt="Red"></a></li>
</ul>

<button name="rgb"><img src="red" alt="RGB"><img src="green" alt=""><img src="blue" alt=""></button>
<button name="cmyk"><img src="cyan" alt="CMYK"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>

<button name="rgb"><img src="red" alt="R"><img src="green" alt="G"><img src="blue" alt="B"></button>
<button name="cmyk"><img src="cyan" alt="C"><img src="magenta" alt="M"><img src="yellow" alt="Y"><img src="black" alt="K"></button>

<button name="rgb"><img src="red" alt="sRGB profile"><img src="green" alt=""><img src="blue" alt=""></button>
<button name="cmyk"><img src="cyan" alt="CMYK profile"><img src="magenta" alt=""><img src="yellow" alt=""><img src="black" alt=""></button>

<p>In the common case, the data handled by the tokenization stage
comes from the network, but it can also come from script.</p>
<p><img src="images/parsing-model-overview.png" alt="The Network
passes data to the Input Stream Preprocessor, which passes it to the
Tokenizer, which passes it to the Tree Construction stage. From there,
data goes to both the DOM and to Script Execution. Script Execution is
linked to the DOM, and, using document.write(), passes data to the
Tokenizer."></p>

<!-- This is the correct way to do things. -->
<p>
 You are standing in an open field west of a house.
 <img src="house.jpeg" alt="The house is white, with a boarded front door.">
 There is a small mailbox here.
</p>

<!-- This is the wrong way to do things. -->
<p>
 You are standing in an open field west of a house.
 <img src="house.jpeg" alt="A white house, with a boarded front door.">
 There is a small mailbox here.
</p>

<nav>
 <p><a href="/help/"><img src="/icons/help.png" alt=""> Help</a></p>
 <p><a href="/configure/"><img src="/icons/configuration.png" alt="">
 Configuration Tools</a></p>
</nav>

<body>
 <article>
  <header>
   <h1>Ratatouille wins <i>Best Movie of the Year</i> award</h1>
   <p><img src="movies.png" alt="Movies"></p>
  </header>
  <p>Pixar has won yet another <i>Best Movie of the Year</i> award,
  making this its 8th win in the last 12 years.</p>
 </article>
 <article>
  <header>
   <h1>Latest TWiT episode is online</h1>
   <p><img src="podcasts.png" alt="Podcasts"></p>
  </header>
  <p>The latest TWiT episode has been posted, in which we hear
  several tech news stories as well as learning much more about the
  iPhone. This week, the panelists compare how reflective their
  iPhones' Apple logos are.</p>
 </article>
</body>

<h1><img src="XYZ.gif" alt="The XYZ company"></h1>

<article>
 <h2>News</h2>
 <p>We have recently been looking at buying the <img src="alpha.gif"
 alt=""> ΑΒΓ company, a small Greek company
 specializing in our type of product.</p>

 <aside><p><img src="alpha-large.gif" alt=""></p></aside>
 <p>The ΑΒΓ company has had a good quarter, and our
 pie chart studies of their accounts suggest a much bigger blue slice
 than its green and orange slices, which is always a good sign.</p>
</article>

<p>Consider for a moment their logo:</p>

<p><img src="/images/logo" alt="It consists of a green circle with a
green question mark centered inside it."></p>

<p>How unoriginal can you get? I mean, oooooh, a question mark, how
<em>revolutionary</em>, how utterly <em>ground-breaking</em>, I'm
sure everyone will rush to adopt those specifications now! They could
at least have tried for some sort of, I don't know, sequence of
rounded squares with varying shades of green and bold white outlines,
at least that would look good on the cover of a blue book.</p>

<h1><img src="earthdayheading.png" alt="Earth Day"></h1>

<p>The Network passes data to the Input Stream Preprocessor, which
passes it to the Tokenizer, which passes it to the Tree Construction
stage. From there, data goes to both the DOM and to Script Execution.
Script Execution is linked to the DOM, and, using document.write(),
passes data to the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png" alt=""></p>

<!-- Using the title="" attribute -->
<p>The Network passes data to the Input Stream Preprocessor, which
passes it to the Tokenizer, which passes it to the Tree Construction
stage. From there, data goes to both the DOM and to Script Execution.
Script Execution is linked to the DOM, and, using document.write(),
passes data to the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png" alt=""
        title="Flowchart representation of the parsing model."></p>

<!-- Using <figure> and <figcaption> -->
<p>The Network passes data to the Input Stream Preprocessor, which
passes it to the Tokenizer, which passes it to the Tree Construction
stage. From there, data goes to both the DOM and to Script Execution.
Script Execution is linked to the DOM, and, using document.write(),
passes data to the Tokenizer.</p>
<figure>
 <img src="images/parsing-model-overview.png" alt="The Network leads to
 the Input Stream Preprocessor, which leads to the Tokenizer, which
 leads to the Tree Construction stage. The Tree Construction stage
 leads to two items. The first is Script Execution, which leads via
 document.write() back to the Tokenizer. The second item from which
 Tree Construction leads is the DOM. The DOM is related to the Script
 Execution.">
 <figcaption>Flowchart representation of the parsing model.</figcaption>
</figure>

<!-- This is WRONG. Do not do this. Instead, do what the above examples do. -->
<p>The Network passes data to the Input Stream Preprocessor, which
passes it to the Tokenizer, which passes it to the Tree Construction
stage. From there, data goes to both the DOM and to Script Execution.
Script Execution is linked to the DOM, and, using document.write(),
passes data to the Tokenizer.</p>
<p><img src="images/parsing-model-overview.png"
        alt="Flowchart representation of the parsing model."></p>
<!-- Never put the image's caption in the alt="" attribute! -->

<p>According to a study covering several billion pages,
about 62% of documents on the Web in 2007 triggered the Quirks
rendering mode of Web browsers, about 30% triggered the Almost
Standards mode, and about 9% triggered the Standards mode.</p>
<p><img src="rendering-mode-pie-chart.png" alt=""></p>

<h1>The Lady of Shalott</h1>
<p><img src="shalott.jpeg" alt=""></p>
<p>On either side the river lie<br>
Long fields of barley and of rye,<br>
That clothe the wold and meet the sky;<br>
And through the field the road run by<br>
To many-tower'd Camelot;<br>
And up and down the people go,<br>
Gazing where the lilies blow<br>
Round an island there below,<br>
The island of Shalott.</p>

<h1><img src="logo1.png" alt="XYZ Corp"><img src="logo2.png" alt=""></h1>

<p>Rating: <meter max=5 value=3><img src="1" alt="3 out of 5"
  ><img src="1" alt=""><img src="1" alt=""><img src="0" alt=""
  ><img src="0" alt=""></meter></p>

<h1>The Church</h1>
<p>You come across a flying spaghetti monster. Which side of His
Noodliness do you wish to reach out for?</p>
<p><a href="?go=left" ><img src="fsm-left.png"  alt="Left side. "></a
  ><img src="fsm-middle.png" alt=""
  ><a href="?go=right"><img src="fsm-right.png" alt="Right side."></a></p>

4.8.1.1.13 Guidance for markup generators

Markup generators (such as WYSIWYG authoring tools) should, wherever possible, obtain alternative text from their users. However, it is recognized that in many cases, this will not be possible.

For images that are the sole contents of links, markup generators should examine the link target to determine the title of the target, or the URL of the target, and use information obtained in this manner as the alternative text.

As a last resort, implementors should either set the alt attribute to the empty string, under the assumption that the image is a purely decorative image that doesn't add any information but is still specific to the surrounding content, or omit the alt attribute altogether, under the assumption that the image is a key part of the content.

Markup generators should generally avoid using the image's own file name as the alternative text. Similarly, markup generators should avoid generating alternative text from any content that will be equally available to presentation user agents (e.g. Web browsers).

This is because once a page is generated, it will typically not be updated, whereas the browsers that later read the page can be updated by the user, therefore the browser is likely to have more up-to-date and finely-tuned heuristics than the markup generator did when generating the page.

4.8.1.1.14 Guidance for conformance checkers

A conformance checker must report the lack of an alt attribute as an error unless one of the conditions listed below applies:

• The title attribute is present and has a non-empty value (as described above).
• The img element is in a figure element that satisfies the conditions described above.
• The conformance checker has been configured to assume that the document is an e-mail or document intended for a specific person who is known to be able to view images.
• The document has a meta element with a name attribute whose value is an ASCII case-insensitive match for the string "generator". (This case does not represent a case where the document is conforming, only that the generator could not determine appropriate alternative text — validators are not required to show an error in this case, because such an error might encourage markup generators to include bogus alternative text purely in an attempt to silence validators. Naturally, conformance checkers may report this error; for example, there could be a user option to report all conformance errors even those that might be the more or less inevitable result of using a markup generator.)

<figure>
 <img src="a-rectangle.png" srcset="a-square.png 600w"
      alt="Barney Frank wears a suit and glasses.">
 <figcaption>Barney Frank, 2011</figcaption>
</figure>

<figure>
 <style scoped>
  #a { width: 300px; height: 150px; }
  @media all and (max-width: 600px) { #a { width: 100px; height: 100px; } }
 </style>
 <img src="a-rectangle.png" srcset="a-square.png 600w" id="a"
      alt="Barney Frank wears a suit and glasses.">
 <figcaption>Barney Frank, 2011</figcaption>
</figure>

<figure>
 <style scoped media="all and (max-width: 600px)">
  #a { width: 100px; height: 100px; }
 </style>
 <img src="a-rectangle.png" width="300" height="100"
      srcset="a-square.png 600w" id=a
      alt="Barney Frank wears a suit and glasses.">
 <figcaption>Barney Frank, 2011</figcaption>
</figure>

<img src="pear-desktop.jpeg" srcset="pear-mobile.jpeg 720w, pear-tablet.jpeg 1280w"
     alt="The pear is juicy.">

<img src="pear-mobile.jpeg"
     srcset="pear-mobile.jpeg 720w, pear-tablet.jpeg 1280w, pear-desktop.jpeg 1x"
     alt="The pear is juicy.">

<img src="pear-tablet.jpeg"
     srcset="pear-mobile.jpeg 720w, pear-tablet.jpeg 1280w, pear-desktop.jpeg 1x"
     alt="The pear is juicy.">

<img src="pear-tablet.jpeg"
     srcset="pear-min0.jpeg 720w, pear-min721.jpeg 1280w, pear-min1281.jpeg 1x"
     alt="The pear is juicy.">