<img>: The Image Embed element - HTML: HyperText Markup Language 编辑
The HTML <img>
element embeds an image into the document.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.The above example shows usage of the <img>
element:
- The
src
attribute is required, and contains the path to the image you want to embed. - The
alt
attribute holds a text description of the image, which isn't mandatory but is incredibly useful for accessibility — screen readers read this description out to their users so they know what the image means. Alt text is also displayed on the page if the image can't be loaded for some reason: for example, network errors, content blocking, or linkrot.
There are many other attributes to achieve various purposes:
- Referrer/CORS control for security and privacy: see
crossorigin
andreferrerpolicy
. - Use both
width
andheight
to set the intrinsic size of the image, allowing it to take up space before it loads, to mitigate content layout shifts. - Responsive image hints with
sizes
andsrcset
(see also the<picture>
element and our Responsive images tutorial).
Supported image formats
The HTML standard doesn't list what image formats to support, so each user agent supports different formats.
The image file formats that are most commonly used on the web are listed below.
Abbreviation | File format | MIME type | File extension(s) | Summary |
---|---|---|---|---|
APNG | Animated Portable Network Graphics | image/apng | .apng | Good choice for lossless animation sequences (GIF is less performant). AVIF and WebP have better performance but less broad browser support. Supported: Chrome, Edge, Firefox, Opera, Safari. |
AVIF | AV1 Image File Format | image/avif | .avif | Good choice for both images and animated images due to high performance and royalty free image format. It offers much better compression than PNG or JPEG with support for higher color depths, animated frames, transparency etc. Note that when using AVIF, you should include fallbacks to formats with better browser support (i.e. using the |
GIF | Graphics Interchange Format | image/gif | .gif | Good choice for simple images and animations. Prefer PNG for lossless and indexed still images, and consider WebP, AVIF or APNG for animation sequences. Supported: Chrome, Edge, Firefox, IE, Opera, Safari. |
JPEG | Joint Photographic Expert Group image | image/jpeg | .jpg , .jpeg , .jfif , .pjpeg , .pjp | Good choice for lossy compression of still images (currently the most popular). Prefer PNG when more precise reproduction of the image is required, or WebP/AVIF if both better reproduction and higher compression are required. |
PNG | Portable Network Graphics | image/png | .png | PNG is preferred over JPEG for more precise reproduction of source images, or when transparency is needed. WebP/AVIF provide even better compression and reproduction, but browser support is more limited. |
SVG | Scalable Vector Graphics | image/svg+xml | .svg | Vector image format; ideal for user interface elements, icons, diagrams, etc., that must be drawn accurately at different sizes. Support: Chrome, Edge, Firefox, IE, Opera, Safari. |
WebP | Web Picture format | image/webp | .webp | Excellent choice for both images and animated images. WebP offers much better compression than PNG or JPEG with support for higher color depths, animated frames, transparency etc. AVIF offers slightly better compression, but is not quite as well-supported in browsers and does not support progressive rendering. Support: Chrome, Edge, Firefox, Opera, Safari |
Note: The older formats like PNG, JPEG, GIF have poor performance compared to newer formats like WebP and AVIF, but enjoy broader "historical" browser support. The newer image formats are seeing increasing popularity as browers without support become increasingly irrelevant (i.e. have virually zero market share).
The following list includes image formats that appear on the web, but which should be avoided for web content (generally this is because either they do not have wide browser support, or because there are better alternatives).
Abbreviation | File format | MIME type | File extension(s) | Description |
---|---|---|---|---|
BMP | Bitmap file | image/bmp | .bmp | Chrome, Edge, Firefox, IE, Opera, Safari |
ICO | Microsoft Icon | image/x-icon | .ico , .cur | Chrome, Edge, Firefox, IE, Opera, Safari |
TIFF | Tagged Image File Format | image/tiff | .tif , .tiff | Safari |
Note: The abbreviation for each image format links to a longer description of the format, its capabilities, and detailed browser compatibility information (including which versions introduced support and specific special features that may have been introduced later).
Note: See Image file type and format guide for more comprehensive information about image formats supported by web browsers. This includes image formats that are supported but not recommended for web content (e.g. ICO, BMP, etc.)
Image loading errors
If an error occurs while loading or rendering an image, and an onerror
event handler has been set on the error
event, that event handler will get called. This can happen in a number of situations, including:
- The
src
attribute is empty (""
) ornull
. - The
src
URL is the same as the URL of the page the user is currently on. - The image is corrupted in some way that prevents it from being loaded.
- The image's metadata is corrupted in such a way that it's impossible to retrieve its dimensions, and no dimensions were specified in the
<img>
element's attributes. - The image is in a format not supported by the user agent.
Attributes
This element includes the global attributes.
alt
- Defines an alternative text description of the image.
Note: Browsers do not always display images. There are a number of situations in which a browser might not display images, such as:
- Non-visual browsers (such as those used by people with visual impairments)
- The user chooses not to display images (saving bandwidth, privacy reasons)
- The image is invalid or an unsupported type
In these cases, the browser may replace the image with the text in the element's
alt
attribute. For these reasons and others, provide a useful value foralt
whenever possible.Omitting
alt
altogether indicates that the image is a key part of the content and no textual equivalent is available. Setting this attribute to an empty string (alt=""
) indicates that this image is not a key part of the content (it’s decoration or a tracking pixel), and that non-visual browsers may omit it from rendering. Visual browsers will also hide the broken image icon if thealt
is empty and the image failed to display.This attribute is also used when copying and pasting the image to text, or saving a linked image to a bookmark.
crossorigin
Indicates if the fetching of the image must be done using a CORS request. Image data from a CORS-enabled image returned from a CORS request can be reused in the
<canvas>
element without being marked "tainted".If the
crossorigin
attribute is not specified, then a non-CORS request is sent (without theOrigin
request header), and the browser marks the image as tainted and restricts access to its image data, preventing its usage in<canvas>
elements.If the
crossorigin
attribute is specified, then a CORS request is sent (with theOrigin
request header); but if the server does not opt into allowing cross-origin access to the image data by the origin site (by not sending anyAccess-Control-Allow-Origin
response header, or by not including the site's origin in anyAccess-Control-Allow-Origin
response header it does send), then the browser marks the image as tainted and restricts access to its image data, preventing its usage in<canvas>
elements.Allowed values:
anonymous
- A CORS request is sent with credentials omitted (that is, no cookies, X.509 certificates, or
Authorization
request header). use-credentials
- The CORS request is sent with any credentials included (that is, cookies, X.509 certificates, and the
Authorization
request header). If the server does not opt into sharing credentials with the origin site (by sending back theAccess-Control-Allow-Credentials: true
response header), then the browser marks the image as tainted and restricts access to its image data.
If the attribute has an invalid value, browsers handle it as if the
anonymous
value was used. See CORS settings attributes for additional information.decoding
Provides an image decoding hint to the browser. Allowed values:
sync
- Decode the image synchronously, for atomic presentation with other content.
async
- Decode the image asynchronously, to reduce delay in presenting other content.
auto
- Default: no preference for the decoding mode. The browser decides what is best for the user.
height
- The intrinsic height of the image, in pixels. Must be an integer without a unit.
intrinsicsize
- This attribute tells the browser to ignore the actual intrinsic size of the image and pretend it’s the size specified in the attribute. Specifically, the image would raster at these dimensions and
naturalWidth
/naturalHeight
on images would return the values specified in this attribute. Explainer, examples ismap
- This Boolean attribute indicates that the image is part of a server-side map. If so, the coordinates where the user clicked on the image are sent to the server.
Note: This attribute is allowed only if the
<img>
element is a descendant of an<a>
element with a validhref
attribute. This gives users without pointing devices a fallback destination. loading
- Indicates how the browser should load the image:
eager
: Loads the image immediately, regardless of whether or not the image is currently within the visible viewport (this is the default value).lazy
: Defers loading the image until it reaches a calculated distance from the viewport, as defined by the browser. The intent is to avoid the network and storage bandwidth needed to handle the image until it's reasonably certain that it will be needed. This generally improves the performance of the content in most typical use cases. Note: Loading is only deferred when JavaScript is enabled. This is an anti-tracking measure, because if a user agent supported lazy loading when scripting is disabled, it would still be possible for a site to track a user's approximate scroll position throughout a session, by strategically placing images in a page's markup such that a server can track how many images are requested and when.
referrerpolicy
- A string indicating which referrer to use when fetching the resource:
no-referrer
: TheReferer
header will not be sent.no-referrer-when-downgrade
: NoReferer
header is sent when navigating to an origin without HTTPS. This is the default if no policy is otherwise specified.origin
: TheReferer
header will include the page's origin (scheme, host, and port).origin-when-cross-origin
: Navigating to other origins will limit the included referral data to the scheme, host, and port, while navigating from the same origin will include the full path and query string.unsafe-url
: TheReferer
header will always include the origin, path and query string, but not the fragment, password, or username. This is unsafe because it can leak information from TLS-protected resources to insecure origins.
sizes
- One or more strings separated by commas, indicating a set of source sizes. Each source size consists of:
- A media condition. This must be omitted for the last item in the list.
- A source size value.
Media Conditions describe properties of the viewport, not of the image. For example,
(max-height: 500px) 1000px
proposes to use a source of 1000px width, if the viewport is not higher than 500px.Source size values specify the intended display size of the image. User agents use the current source size to select one of the sources supplied by the
srcset
attribute, when those sources are described using width (w
) descriptors. The selected source size affects the intrinsic size of the image (the image’s display size if no CSS styling is applied). If thesrcset
attribute is absent, or contains no values with a width descriptor, then thesizes
attribute has no effect. src
- The image URL. Mandatory for the
<img>
element. On browsers supportingsrcset
,src
is treated like a candidate image with a pixel density descriptor1x
, unless an image with this pixel density descriptor is already defined insrcset
, or unlesssrcset
containsw
descriptors. srcset
- One or more strings separated by commas, indicating possible image sources for the user agent to use. Each string is composed of:
- A URL to an image
- Optionally, whitespace followed by one of:
- A width descriptor (a positive integer directly followed by
w
). The width descriptor is divided by the source size given in thesizes
attribute to calculate the effective pixel density. - A pixel density descriptor (a positive floating point number directly followed by
x
).
- A width descriptor (a positive integer directly followed by
If no descriptor is specified, the source is assigned the default descriptor of
1x
.It is incorrect to mix width descriptors and pixel density descriptors in the same
srcset
attribute. Duplicate descriptors (for instance, two sources in the samesrcset
which are both described with2x
) are also invalid.The user agent selects any of the available sources at its discretion. This provides them with significant leeway to tailor their selection based on things like user preferences or bandwidth conditions. See our Responsive images tutorial for an example.
width
- The intrinsic width of the image in pixels. Must be an integer without a unit.
usemap
- The partial URL (starting with
#
) of an image map associated with the element.Note: You cannot use this attribute if the
<img>
element is inside an<a>
or<button>
element.
Deprecated attributes
align
- Aligns the image with its surrounding context. Use the
float
and/orvertical-align
CSS properties instead of this attribute. Allowed values: top
- Equivalent to
vertical-align: top
orvertical-align: text-top
middle
- Equivalent to
vertical-align: -moz-middle-with-baseline
bottom
- The default, equivalent to
vertical-align: unset
orvertical-align: initial
left
- Equivalent to
float: left
right
- Equivalent to
float: right
border
- The width of a border around the image. Use the
border
CSS property instead. hspace
- The number of pixels of white space on the left and right of the image. Use the
margin
CSS property instead. longdesc
- A link to a more detailed description of the image. Possible values are a URL or an element
id
.Note: This attribute is mentioned in the latest W3C version, HTML 5.2, but has been removed from the WHATWG’s HTML Living Standard. It has an uncertain future; authors should use a WAI-ARIA alternative such as
aria-describedby
oraria-details
. name
- A name for the element. Use the
id
attribute instead. vspace
- The number of pixels of white space above and below the image. Use the
margin
CSS property instead.
Styling with CSS
<img>
is a replaced element; it has a display
value of inline
by default, but its default dimensions are defined by the embedded image's intrinsic values, like it were inline-block
. You can set properties like border
/border-radius
, padding
/margin
, width
, height
, etc. on an image.
<img>
has no baseline, so when images are used in an inline formatting context with vertical-align
: baseline
, the bottom of the image will be placed on the text baseline.
You can use the object-position
property to position the image within the element's box, and the object-fit
property to adjust the sizing of the image within the box (for example, whether the image should fit the box or fill it even if clipping is required).
Depending on its type, an image may have an intrinsic width and height. For some image types, however, intrinsic dimensions are unnecessary. SVG images, for instance, have no intrinsic dimensions if their root <svg>
element doesn't have a width
or height
set on it.
Examples
Alternative text
The following example embeds an image into the page and includes alternative text for accessibility.
<img src="https://www.wenjiangs.com/wp-content/uploads/2020/mozilla/favicon144.png"
alt="MDN logo">
Image link
This example builds upon the previous one, showing how to turn the image into a link. To do so, nest the <img>
tag inside the <a>
. You should made the alternative text describe the resource the link is pointing to, as if you were using a text link instead.
<a href="https://developer.mozilla.org">
<img src="https://www.wenjiangs.com/wp-content/uploads/2020/mozilla/favicon144.png"
alt="Visit the MDN site">
</a>
Using the srcset attribute
In this example we include a srcset
attribute with a reference to a high-resolution version of the logo; this will be loaded instead of the src
image on high-resolution devices. The image referenced in the src
attribute is counted as a 1x
candidate in user agents that support srcset
.
<img src="https://www.wenjiangs.com/wp-content/uploads/2020/mozilla/favicon72.png"
alt="MDN logo"
srcset="https://www.wenjiangs.com/wp-content/uploads/2020/mozilla/favicon144.png 2x">
Using the srcset and sizes attributes
The src
attribute is ignored in user agents that support srcset
when w
descriptors are included. When the (max-width: 600px)
media condition matches, the 200 pixel-wide image will load (it is the one that matches 200px
most closely), otherwise the other image will load.
<img src="/files/16864/clock-demo-200px.png"
alt="Clock"
srcset="/files/16864/clock-demo-200px.png 200w,
/files/16797/clock-demo-400px.png 400w"
sizes="(max-width: 600px) 200px, 50vw">
To see the resizing in action, view the example on a separate page, so you can actually resize the content area.
Security and privacy concerns
Although <img>
elements have innocent uses, they can have undesirable consequences for user security and privacy. See Referer header: privacy and security concerns for more information and mitigations.
Accessibility concerns
Authoring meaningful alternate descriptions
An alt
attribute's value should clearly and concisely describe the image's content. It should not describe the presence of the image itself or the file name of the image. If the alt
attribute is purposefully left off because the image has no textual equivalent, consider alternate methods to present what the image is trying to communicate.
Don't
<img alt="image" src="penguin.jpg">
Do
<img alt="A Rockhopper Penguin standing on a beach." src="penguin.jpg">
When an alt
attribute is not present on an image, some screen readers may announce the image's file name instead. This can be a confusing experience if the file name isn't representative of the image's contents.
- An alt Decision Tree • Images • WAI Web Accessibility Tutorials
- Alt-texts: The Ultimate Guide — Axess Lab
- How to Design Great Alt Text: An Introduction | Deque
- MDN Understanding WCAG, Guideline 1.1 explanations
- Understanding Success Criterion 1.1.1 | W3C Understanding WCAG 2.0
The title attribute
The title
attribute is not an acceptable substitute for the alt
attribute. Additionally, avoid duplicating the alt
attribute's value in a title
attribute declared on the same image. Doing so may cause some screen readers to announce the description twice, creating a confusing experience.
The title
attribute should also not be used as supplemental captioning information to accompany an image's alt
description. If an image needs a caption, use the figure
and figcaption
elements.
The value of the title
attribute is usually presented to the user as a tooltip, which appears shortly after the cursor stops moving over the image. While this can provide additional information to the user, you should not assume that the user will ever see it: the user may only have keyboard or touchscreen. If you have information that's particularly important or valuable for the user, present it inline using one of the methods mentioned above instead of using title
.
Technical summary
Content categories | Flow content, phrasing content, embedded content, palpable content. If the element has a usemap attribute, it also is a part of the interactive content category. |
---|---|
Permitted content | None, it is an empty element. |
Tag omission | Must have a start tag and must not have an end tag. |
Permitted parents | Any element that accepts embedded content. |
Implicit ARIA role |
|
Permitted ARIA roles |
|
DOM interface | HTMLImageElement |
Specifications
Specification | Status | Comment |
---|---|---|
Referrer Policy The definition of 'referrer attribute' in that specification. | Candidate Recommendation | Added the referrerpolicy attribute. |
HTML Living Standard The definition of '<img>' in that specification. | Living Standard | |
HTML5 The definition of '<img>' in that specification. | Recommendation | |
HTML 4.01 Specification The definition of '<img>' in that specification. | Recommendation |
Browser compatibility
BCD tables only load in the browser
See also
- Images in HTML
- Image file type and format guide
- Responsive images
<picture>
,<object>
and<embed>
elements- Other image-related CSS properties:
object-fit
,object-position
,image-orientation
,image-rendering
, andimage-resolution
.
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