HTML Attributes

Attribute	Element(s)	Description	Value
`abbr`	`th`	Alternative label to use for the header cell when referencing the cell in other contexts	Text*
`accept`	`input`	Hint for expected file type in file upload controls	Set of comma-separated tokens* consisting of valid MIME types with no parameters or `audio/`, `video/`, or `image/*`
`accept-charset`	`form`	Character encodings to use for form submission	Ordered set of unique space-separated tokens, ASCII case-insensitive, consisting of names of ASCII-compatible character encodings*
`accesskey`	HTML elements	Keyboard shortcut to activate or focus element	Ordered set of unique space-separated tokens, case-sensitive, consisting of one Unicode code point in length
`action`	`form`	URL to use for form submission	Valid non-empty URL potentially surrounded by spaces
`allowfullscreen`	`iframe`	Whether to allow the `iframe`'s contents to use `requestFullscreen()`	Boolean attribute
`alt`	`area`; `img`; `input`	Replacement text for use when images are not available	Text*
`async`	`script`	Execute script asynchronously	Boolean attribute
`autocomplete`	`form`	Default setting for autofill feature for controls in the form	"`on`"; "`off`"
`autocomplete`	`input`; `select`; `textarea`	Hint for form autofill feature	Autofill field name and related tokens*
`autofocus`	`button`; `input`; `keygen`; `select`; `textarea`	Automatically focus the form control when the page is loaded	Boolean attribute
`autoplay`	`audio`; `video`	Hint that the media resource can be started automatically when the page is loaded	Boolean attribute
`challenge`	`keygen`	String to package with the generated and signed public key	Text
`charset`	`meta`	Character encoding declaration	Encoding name*
`charset`	`script`	Character encoding of the external script resource	Encoding name*
`checked`	`menuitem`; `input`	Whether the command or control is checked	Boolean attribute
`cite`	`blockquote`; `del`; `ins`; `q`	Link to the source of the quotation or more information about the edit	Valid URL potentially surrounded by spaces
`class`	HTML elements	Classes to which the element belongs	Set of space-separated tokens
`cols`	`textarea`	Maximum number of characters per line	Valid non-negative integer greater than zero
`colspan`	`td`; `th`	Number of columns that the cell is to span	Valid non-negative integer greater than zero
`command`	`menuitem`	Command definition	ID*
`content`	`meta`	Value of the element	Text*
`contenteditable`	HTML elements	Whether the element is editable	"`true`"; "`false`"
`contextmenu`	HTML elements	The element's context menu	ID*
`controls`	`audio`; `video`	Show user agent controls	Boolean attribute
`coords`	`area`	Coordinates for the shape to be created in an image map	Valid list of integers*
`crossorigin`	`audio`; `img`; `link`; `script`; `video`	How the element handles crossorigin requests	"`anonymous`"; "`use-credentials`"
`data`	`object`	Address of the resource	Valid non-empty URL potentially surrounded by spaces
`datetime`	`del`; `ins`	Date and (optionally) time of the change	Valid date string with optional time
`datetime`	`time`	Machine-readable value	Valid month string, valid date string, valid yearless date string, valid time string, valid local date and time string, valid time-zone offset string, valid global date and time string, valid week string, valid non-negative integer, or valid duration string
`default`	`track`	Enable the track if no other text track is more suitable	Boolean attribute
`defer`	`script`	Defer script execution	Boolean attribute
`dir`	HTML elements	The text directionality of the element	"`ltr`"; "`rtl`"; "`auto`"
`dirname`	`input`; `textarea`	Name of form field to use for sending the element's directionality in form submission	Text*
`disabled`	`button`; `menuitem`; `fieldset`; `input`; `keygen`; `optgroup`; `option`; `select`; `textarea`	Whether the form control is disabled	Boolean attribute
`download`	`a`; `area`	Whether to download the resource instead of navigating to it, and its file name if so	Text
`draggable`	HTML elements	Whether the element is draggable	"`true`"; "`false`"
`dropzone`	HTML elements	Accepted item types for drag-and-drop	Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of accepted types and drag feedback*
`enctype`	`form`	Form data set encoding type to use for form submission	"`application/x-www-form-urlencoded`"; "`multipart/form-data`"; "`text/plain`"
`for`	`label`	Associate the label with form control	ID*
`for`	`output`	Specifies controls from which the output was calculated	Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs*
`form`	`button`; `fieldset`; `input`; `keygen`; `label`; `object`; `output`; `select`; `textarea`	Associates the control with a `form` element	ID*
`formaction`	`button`; `input`	URL to use for form submission	Valid non-empty URL potentially surrounded by spaces
`formenctype`	`button`; `input`	Form data set encoding type to use for form submission	"`application/x-www-form-urlencoded`"; "`multipart/form-data`"; "`text/plain`"
`formmethod`	`button`; `input`	HTTP method to use for form submission	"`GET`"; "`POST`"
`formnovalidate`	`button`; `input`	Bypass form control validation for form submission	Boolean attribute
`formtarget`	`button`; `input`	Browsing context for form submission	Valid browsing context name or keyword
`headers`	`td`; `th`	The header cells for this cell	Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs*
`height`	`canvas`; `embed`; `iframe`; `img`; `input`; `object`; `video`	Vertical dimension	Valid non-negative integer
`hidden`	HTML elements	Whether the element is relevant	Boolean attribute
`high`	`meter`	Low limit of high range	Valid floating-point number*
`href`	`a`; `area`	Address of the hyperlink	Valid URL potentially surrounded by spaces
`href`	`link`	Address of the hyperlink	Valid non-empty URL potentially surrounded by spaces
`href`	`base`	Document base URL	Valid URL potentially surrounded by spaces
`hreflang`	`a`; `area`; `link`	Language of the linked resource	Valid BCP 47 language tag
`http-equiv`	`meta`	Pragma directive	Text*
`icon`	`menuitem`	Icon for the command	Valid non-empty URL potentially surrounded by spaces
`id`	HTML elements	The element's ID	Text*
`inert`	HTML elements	Whether the element is inert	Boolean attribute
`inputmode`	`input`; `textarea`	Hint for selecting an input modality	`verbatim`; `latin`; `latin-name`; `latin-prose`; `full-width-latin`; `kana`; `katakana`; `numeric`; `tel`; `email`; `url`
`ismap`	`img`	Whether the image is a server-side image map	Boolean attribute
`itemid`	HTML elements	Global identifier for a microdata item	Valid URL potentially surrounded by spaces
`itemprop`	HTML elements	Property names of a microdata item	Unordered set of unique space-separated tokens, case-sensitive, consisting of valid absolute URLs, defined property names, or text*
`itemref`	HTML elements	Referenced elements	Unordered set of unique space-separated tokens, case-sensitive, consisting of IDs*
`itemscope`	HTML elements	Introduces a microdata item	Boolean attribute
`itemtype`	HTML elements	Item types of a microdata item	Unordered set of unique space-separated tokens, case-sensitive, consisting of valid absolute URL*
`keytype`	`keygen`	The type of cryptographic key to generate	Text*
`kind`	`track`	The type of text track	"`subtitles`"; "`captions`"; "`descriptions`"; "`chapters`"; "`metadata`"
`label`	`menuitem`; `menu`; `optgroup`; `option`; `track`	User-visible label	Text
`lang`	HTML elements	Language of the element	Valid BCP 47 language tag or the empty string
`list`	`input`	List of autocomplete options	ID*
`loop`	`audio`; `video`	Whether to loop the media resource	Boolean attribute
`low`	`meter`	High limit of low range	Valid floating-point number*
`manifest`	`html`	Application cache manifest	Valid non-empty URL potentially surrounded by spaces
`max`	`input`	Maximum value	Varies*
`max`	`meter`; `progress`	Upper bound of range	Valid floating-point number*
`maxlength`	`input`; `textarea`	Maximum length of value	Valid non-negative integer
`media`	`link`; `source`; `style`	Applicable media	Valid media query
`mediagroup`	`audio`; `video`	Groups media elements together with an implicit `MediaController`	Text
`method`	`form`	HTTP method to use for form submission	"`GET`"; "`POST`"; "`dialog`"
`min`	`input`	Minimum value	Varies*
`min`	`meter`	Lower bound of range	Valid floating-point number*
`multiple`	`input`; `select`	Whether to allow multiple values	Boolean attribute
`muted`	`audio`; `video`	Whether to mute the media resource by default	Boolean attribute
`name`	`button`; `fieldset`; `input`; `keygen`; `output`; `select`; `textarea`	Name of form control to use for form submission and in the `form.elements` API	Text*
`name`	`form`	Name of form to use in the `document.forms` API	Text*
`name`	`iframe`; `object`	Name of nested browsing context	Valid browsing context name or keyword
`name`	`map`	Name of image map to reference from the `usemap` attribute	Text*
`name`	`meta`	Metadata name	Text*
`name`	`param`	Name of parameter	Text
`novalidate`	`form`	Bypass form control validation for form submission	Boolean attribute
`open`	`details`	Whether the details are visible	Boolean attribute
`open`	`dialog`	Whether the dialog box is showing	Boolean attribute
`optimum`	`meter`	Optimum value in gauge	Valid floating-point number*
`pattern`	`input`	Pattern to be matched by the form control's value	Regular expression matching the JavaScript Pattern production
`ping`	`a`; `area`	URLs to ping	Set of space-separated tokens consisting of valid non-empty URLs
`placeholder`	`input`; `textarea`	User-visible label to be placed within the form control	Text*
`poster`	`video`	Poster frame to show prior to video playback	Valid non-empty URL potentially surrounded by spaces
`preload`	`audio`; `video`	Hints how much buffering the media resource will likely need	"`none`"; "`metadata`"; "`auto`"
`radiogroup`	`menuitem`	Name of group of commands to treat as a radio button group	Text
`readonly`	`input`; `textarea`	Whether to allow the value to be edited by the user	Boolean attribute
`rel`	`a`; `area`; `link`	Relationship between the document containing the hyperlink and the destination resource	Set of space-separated tokens*
`required`	`input`; `select`; `textarea`	Whether the control is required for form submission	Boolean attribute
`reversed`	`ol`	Number the list backwards	Boolean attribute
`rows`	`textarea`	Number of lines to show	Valid non-negative integer greater than zero
`rowspan`	`td`; `th`	Number of rows that the cell is to span	Valid non-negative integer
`sandbox`	`iframe`	Security rules for nested content	Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of "`allow-forms`", "`allow-pointer-lock`", "`allow-popups`", "`allow-same-origin`", "`allow-scripts` and "`allow-top-navigation`"
`spellcheck`	HTML elements	Whether the element is to have its spelling and grammar checked	"`true`"; "`false`"
`scope`	`th`	Specifies which cells the header cell applies to	"`row`"; "`col`"; "`rowgroup`"; "`colgroup`"
`scoped`	`style`	Whether the styles apply to the entire document or just the parent subtree	Boolean attribute
`seamless`	`iframe`	Whether to apply the document's styles to the nested content	Boolean attribute
`selected`	`option`	Whether the option is selected by default	Boolean attribute
`shape`	`area`	The kind of shape to be created in an image map	"`circle`"; "`default`"; "`poly`"; "`rect`"
`size`	`input`; `select`	Size of the control	Valid non-negative integer greater than zero
`sizes`	`link`	Sizes of the icons (for `rel`="`icon`")	Unordered set of unique space-separated tokens, ASCII case-insensitive, consisting of sizes*
`span`	`col`; `colgroup`	Number of columns spanned by the element	Valid non-negative integer greater than zero
`src`	`audio`; `embed`; `iframe`; `img`; `input`; `script`; `source`; `track`; `video`	Address of the resource	Valid non-empty URL potentially surrounded by spaces
`srcdoc`	`iframe`	A document to render in the `iframe`	The source of an `iframe` `srcdoc` document*
`srclang`	`track`	Language of the text track	Valid BCP 47 language tag
`srcset`	`img`	Images to use in different situations (e.g. high-resolution displays, small monitors, etc)	Comma-separated list of image candidate strings
`start`	`ol`	Ordinal value of the first item	Valid integer
`step`	`input`	Granularity to be matched by the form control's value	Valid floating-point number greater than zero, or "`any`"
`style`	HTML elements	Presentational and formatting instructions	CSS declarations*
`tabindex`	HTML elements	Whether the element is focusable, and the relative order of the element for the purposes of sequential focus navigation	Valid integer
`target`	`a`; `area`	Browsing context for hyperlink navigation	Valid browsing context name or keyword
`target`	`base`	Default browsing context for hyperlink navigation and form submission	Valid browsing context name or keyword
`target`	`form`	Browsing context for form submission	Valid browsing context name or keyword
`title`	HTML elements	Advisory information for the element	Text
`title`	`abbr`; `dfn`	Full term or expansion of abbreviation	Text
`title`	`menuitem`	Hint describing the command	Text
`title`	`link`	Title of the link	Text
`title`	`link`; `style`	Alternative style sheet set name	Text
`translate`	HTML elements	Whether the element is to be translated when the page is localized	"`yes`"; "`no`"
`type`	`a`; `area`; `link`	Hint for the type of the referenced resource	Valid MIME type
`type`	`button`	Type of button	"`submit`"; "`reset`"; "`button`"; "`menu`"
`type`	`embed`; `object`; `script`; `source`; `style`	Type of embedded resource	Valid MIME type
`type`	`input`	Type of form control	`input` type keyword
`type`	`menu`	Type of menu	"`popup`"; "`toolbar`"
`type`	`menuitem`	Type of command	"`command`"; "`checkbox`"; "`radio`"
`type`	`ol`	Kind of list marker	"`1`"; "`a`"; "`A`"; "`i`"; "`I`"
`typemustmatch`	`object`	Whether the `type` attribute and the Content-Type value need to match for the resource to be used	Boolean attribute
`usemap`	`img`; `object`	Name of image map to use	Valid hash-name reference*
`value`	`button`; `option`	Value to be used for form submission	Text
`value`	`data`	Machine-readable value	Text*
`value`	`input`	Value of the form control	Varies*
`value`	`li`	Ordinal value of the list item	Valid integer
`value`	`meter`; `progress`	Current value of the element	Valid floating-point number
`value`	`param`	Value of parameter	Text
`width`	`canvas`; `embed`; `iframe`; `img`; `input`; `object`; `video`	Horizontal dimension	Valid non-negative integer
`wrap`	`textarea`	How the value of the form control is to be wrapped for form submission	"`soft`"; "`hard`"

Event handler content attributes not included.
An asterisk (*) in a cell indicates that the actual rules are more complicated than indicated in the table above.