🗃️🏷️ Ethan's HTML Attribute Reference

Provides an abbreviated label for a table header cell.

Provides an abbreviated form of a table header's content in older table models. It was intended to give user agents a shorter label for repeated or compact presentation, but it is rarely used in modern HTML.

Indicates whether an operator or script should be treated as an accent.

Indicates in MathML whether an over- or under-script should be treated as an accent. This can affect spacing and script sizing.

Historically specifies the distance from the font origin to the top of accent characters in an SVG font.

Indicates whether an underscript should be treated as an accent.

Indicates whether an underscript in MathML should be treated as an accent. It is mainly relevant to munder and munderover layout.

Specifies accepted input or upload types.

Specifies which file or media types are acceptable for a control, most commonly an input with type="file". Its value is a comma-separated list of MIME types, filename extensions, or broad media categories such as image/*.

Specifies the character encoding used for form submission.

Specifies the character encoding to use when a form is submitted. In modern HTML, UTF-8 is the expected encoding, so this attribute has far less practical variety than it once did.

Provides a keyboard shortcut hint for activating or focusing an element.

Assigns a keyboard shortcut hint to an element. The actual key combination depends on the browser and operating system, so authors should not assume one universal shortcut sequence.

Controls whether animation values accumulate across repeated iterations.

Specifies the URL that processes a submitted form.

Sets the URL that receives a form submission. It is used on form and can be overridden for individual submit controls with formaction.

Specifies the action behavior of a legacy MathML maction element.

Controls whether an animation adds to or replaces the underlying value.

Historically controls element alignment in HTML and is also used in some MathML table contexts.

Historically controlled horizontal or vertical alignment on elements such as images, tables, rows, cells, captions, and horizontal rules. Modern documents use CSS for alignment instead, but the attribute still appears frequently in older HTML and email markup.

Specifies how an element is aligned relative to the dominant baseline.

Historically sets the color of active hyperlinks on the body element.

Historically set the color used for an active link, usually on body. CSS pseudo-classes such as :active replaced this document-wide presentational setting.

Specifies permissions policy features allowed for an iframe.

Sets a Permissions Policy for an iframe, controlling which browser features the embedded document may use. Common feature names include camera, microphone, geolocation, fullscreen, and autoplay.

Allows an iframe's content to request fullscreen presentation; a legacy alias for an appropriate Permissions Policy.

Allows an iframe to enter fullscreen mode when requested by its contents. Modern permissions handling overlaps with the allow attribute, but allowfullscreen remains widely encountered in embed code.

Legacy iframe attribute allowing the Payment Request API in a cross-origin frame.

Was used on iframe to allow the embedded document to use the Payment Request API. The feature was folded into Permissions Policy behavior and the dedicated attribute is obsolete.

Historically allowed iframe backgrounds to appear transparent in Internet Explorer.

Legacy Chromium iframe attribute used before Permissions Policy to allow camera or microphone access.

Allows alpha transparency in a color input where supported.

Allows a color input to accept an alpha channel in addition to the color itself. It is associated with newer color-input behavior and may not be supported uniformly across browsers.

Historically specifies the alphabetic baseline position in an SVG font.

Provides alternative text for images and certain image-based controls.

Provides a text alternative for an image or image-like control. It is especially important on img, where the value should communicate the image's purpose or content when the image is unavailable or nonvisual access is being used.

Sets the amplitude of the gamma function used by a component transfer filter.

Associates a positioned element with an anchor element for CSS anchor positioning.

Historically identifies the positional form of an Arabic glyph in an SVG font.

Historically specified archives associated with an applet or object.

Historically listed archives containing resources needed by an embedded Java applet or object. It belongs to the old plugin and applet model rather than modern browser resource loading.

Family of ARIA states and properties used to describe accessibility semantics.

Represents the family of ARIA state and property attributes used to expose accessibility information. Specific members such as aria-label, aria-expanded, aria-controls, and aria-live have distinct rules and should be used according to the element's allowed accessibility semantics.

Specifies the expected resource type for a preload or related link.

Tells the browser what type of resource a link is expected to fetch, particularly with rel values such as preload. Values such as script, style, image, font, and fetch help the browser apply the correct loading behavior and security rules.

Historically specifies the maximum unaccented height of an SVG font.

Allows a script to execute asynchronously when available.

Makes an external script load independently of HTML parsing and execute as soon as it is ready. Because execution order is not preserved among ordinary async scripts, it is best suited to scripts that do not depend on one another.

Names the attribute or property targeted by an SVG animation.

Names the SVG attribute or property targeted by an animation element such as animate. The animation changes that named value over its active duration.

Historically specifies the namespace/type of an animated attribute.

Historically indicated whether an SVG animation target was an XML attribute or CSS property. Modern SVG processing largely infers this and the attribute is considered obsolete in newer specifications.

Requests Attribution Reporting registration for a navigation or resource request.

Controls automatic capitalization of user-entered text.

Controls automatic capitalization behavior in editable text, especially on mobile keyboards. It can request behavior such as no capitalization, sentence capitalization, word capitalization, or character capitalization.

Controls or hints browser autofill behavior.

Controls whether and how browsers may autofill form fields. Beyond simple on and off values, it supports tokens such as name, email, postal-code, current-password, and one-time-code that tell the browser what kind of information a control expects.

Controls automatic correction of editable text.

Requests that an element receive focus automatically.

Requests that an element receive focus automatically when the page or dialog becomes active. It is most often used on form controls, though automatically moving focus can be disruptive if used without a clear reason.

Requests immediate location retrieval when a geolocation element is rendered and permission was previously granted.

Requests automatic playback of media.

Requests that audio or video begin playing automatically when possible. Browsers commonly restrict autoplay, especially when sound is enabled, so the attribute should not be treated as a guarantee that playback will start.

Legacy WebKit attribute naming saved search suggestions for a search input.

Experimental RFC 1942 table-cell attribute listing axis names associated with a cell; superseded by later table accessibility mechanisms.

Historically categorized table cells along conceptual axes.

Was used on table cells to place them into conceptual categories that could help describe multidimensional table data. The attribute never became a common authoring tool and is obsolete in modern HTML.

Specifies the horizontal direction of a distant light source.

Historically specifies a background image URL on body and table-related elements.

Historically set a background image URL directly on elements such as body or table cells. CSS background-image replaced this presentational attribute for normal web authoring.

Sets the base frequency used to generate turbulence noise.

Controls the base frequency of procedural noise generated by feTurbulence. One or two numbers set the horizontal and vertical frequency of the noise pattern.

Shifts an element's dominant baseline relative to its parent.

Declares the minimum SVG language profile required by a document.

Historically specifies the bounding box of an SVG font face.

Specifies when an SVG animation begins.

Sets when an SVG SMIL animation begins. It can use clock values, event-based triggers, or references to other animation timings.

Controls the scrolling behavior of the non-standard marquee element.

Historically specifies an element's background color.

Historically set an element's background color, commonly on body, tables, rows, and cells. It remains common in legacy HTML and email templates, where old rendering engines sometimes still influence authoring choices.

Adds a constant bias to each component of a convolution filter result.

Specifies operations, such as rendering, that may be blocked while an external resource is fetched.

Hints that certain rendering or execution work should block a particular processing stage, such as rendering. It is a newer low-level loading-control attribute used on a small set of elements including script, style, and link.

Historically specifies a border width on certain HTML elements; legacy presentational markup superseded by CSS.

Historically controlled the visible border around elements such as tables, images, and objects. CSS now handles border styling, though old markup frequently contains numeric border values and img border="0" was once a common way to suppress link-image borders.

Historically specifies the color of table or frame borders.

Was a proprietary or legacy presentational attribute for setting border color on tables and other elements. CSS border-color is the modern mechanism.

Historically sets the bottom body margin in pixels.

Requests that selected Topics API interests be sent with an iframe request.

Requests participation in the browser's Topics advertising API on supported requests. It is privacy-sandbox-related and far more specialized than ordinary resource-loading attributes.

Specifies a relative offset value for an SVG animation.

Specifies the interpolation mode used by an SVG animation.

Controls how values are interpolated in an SVG animation. Modes include discrete, linear, paced, and spline interpolation.

Historically specifies the height of uppercase glyphs in an SVG font.

Hints that file input should use a device capture mechanism.

Hints that a file input should capture new media using a device camera or microphone instead of only selecting an existing file. It is generally paired with accept on input type="file" and is most relevant on mobile devices.

Historically specifies padding inside table cells.

Historically set the amount of space between a table cell's content and its border. CSS padding on td and th provides the modern equivalent.

Historically specifies spacing between table cells.

Historically set the amount of space between adjacent table cells. Modern table spacing is controlled with CSS properties such as border-spacing and border-collapse.

Historically specifies the alignment character for table columns or cells.

Historically identified a character used to align table-cell contents, such as a decimal point. It was tied to old table alignment features and is no longer used in modern HTML authoring.

Historically specifies an offset from the alignment character in a table.

Historically adjusted alignment relative to the character specified by char in table-related elements. It is an obsolete table-formatting attribute with little relevance to current browser layout.

Declares a character encoding in contexts where the attribute remains valid.

Declares a character encoding in contexts where the attribute is defined, most notably meta. Older HTML also allowed charset on several linking and scripting elements, uses that are now obsolete.

Sets the initial checked state of a checkbox or radio control.

Sets the initial checked state of a checkbox or radio input. For radio buttons sharing the same name, the checked state identifies which option starts selected.

Provides a URL identifying the source of a quotation or edit.

Provides a URL identifying the source or explanation for a quotation or document change. It is used on elements such as blockquote, q, del, and ins, and is metadata rather than a visible citation by itself.

Assigns one or more CSS/DOM class names.

Assigns one or more class names to an element. Classes are widely used as hooks for CSS, JavaScript, testing, and other systems that need to identify groups of elements.

Historically identifies an implementation for an object element.

Historically identified the implementation of an embedded object, often a browser plugin or ActiveX control. It is strongly associated with the old plugin web.

Historically controls text flow around floated content.

Historically controlled how elements such as br interacted with floated content, with values indicating which side should be cleared. CSS clear replaced this presentational attribute.

Defines a clipping rectangle using legacy CSS clipping syntax.

Associates an element with a clipping path.

Determines which parts of a shape are inside a clipping path.

Defines the coordinate system used by a clipPath's contents.

Sets the coordinate system used by an SVG clipPath. It determines whether clip geometry is interpreted in user space or relative to the target element's bounding box.

Specifies the closing delimiter used by a legacy MathML mfenced element.

Specifies which user actions are allowed to close a dialog.

Historically names the applet class or object code to load.

Historically named the Java class file to run inside an applet. It is part of the obsolete Java applet embedding model.

Historically specifies a base URL for applet or object resources.

Historically supplied a base URL for locating applet or object resources. It was mainly associated with Java and plugin content and has no normal role in modern HTML.

Historically declares the MIME type of code used by an object.

Historically declared the expected content type of code associated with an object. It belonged to older object/plugin loading mechanisms and is obsolete.

Specifies color in SVG presentation contexts; the same name was also used by obsolete presentational HTML markup.

Historically specified a text or rule color directly in markup, especially on font and some presentational elements. CSS color and related properties replaced these uses in modern HTML.

Specifies the color space used for color interpolation.

Specifies the color space used for filter-effect interpolation.

Selects the color space used to serialize a color input's value.

Specifies the visible width of a textarea in character columns.

Sets a visible width in character columns for certain text-entry or historical layout elements. It is most familiar on textarea, where it provides an initial sizing hint rather than a hard limit on entered text.

Specifies how many table columns a cell spans.

Makes a table cell span more than one column. It is used on td and th and is important when the logical structure of a row does not map one-to-one to the table's column grid.

Specifies horizontal alignment of MathML table cells.

Controls horizontal alignment of columns in MathML tables. Values can be applied across one or more columns.

Specifies line styles between MathML table columns.

Controls dividing lines between MathML table columns. It accepts line-style values for the boundaries between columns.

Specifies spacing between MathML table columns.

Sets spacing between columns in a MathML table. It is the mathematical-table counterpart to ordinary table gap control.

Specifies how many MathML table columns a cell spans.

Specifies the action a command-invoking button requests from its target.

Identifies the element targeted by a command-invoking button.

Historically requests compact rendering of certain lists.

Historically requested a more compact presentation for certain lists and related elements. It was purely presentational and was replaced by CSS.

Provides the value associated with metadata declared by a meta element.

Supplies the value associated with a meta element's metadata declaration. Its meaning depends on the accompanying name, http-equiv, or other metadata context.

Controls whether an element's contents can be edited.

Makes an element's contents editable by the user when enabled. The browser provides basic editing behavior, while scripts can observe or manipulate the resulting DOM changes.

Historically associates an element with a context menu.

Requests built-in media playback controls.

Requests the browser's built-in playback controls for audio or video. The exact appearance varies by browser, but commonly includes play/pause, seeking, volume, and fullscreen controls where applicable.

Hints which built-in controls a browser should expose for audio or video.

Provides hints about which native media controls should be omitted from an audio or video element. Values can request restrictions such as hiding download, remote playback, or fullscreen controls where the browser supports them.

Specifies coordinates for an image-map area.

Defines coordinates for a clickable region in an image map, usually on area. The required number and interpretation of coordinates depend on the associated shape value.

Loads an iframe in a credentialless ephemeral context.

Loads an iframe in a special credentialless context that omits credentials and storage normally associated with cross-origin requests. It is used in advanced cross-origin isolation scenarios.

Controls CORS behavior for external resources.

Controls how a cross-origin request is made for resources such as images, scripts, fonts, audio, video, and links. Values such as anonymous and use-credentials determine whether credentials are sent and whether CORS rules permit the result to be used in certain APIs.

Specifies a Content Security Policy for an iframe's embedded document.

Supplies a Content Security Policy for an embedded iframe in implementations that support the attribute. It is a specialized security control and is not broadly used in ordinary markup.

Specifies the mouse cursor displayed when pointing at an element.

Specifies the x-coordinate of a center point.

Sets the x-coordinate of the center of an SVG circle, ellipse, or radial gradient where applicable. Its exact role depends on the SVG element carrying it.

Specifies the y-coordinate of a center point.

Sets the y-coordinate of the center of an SVG circle, ellipse, or radial gradient. It is one of the common SVG geometry attributes.

Defines the shape of an SVG path.

Contains path data for an SVG path element. The compact command syntax describes moves, straight lines, Bézier curves, arcs, and path closure.

Specifies the resource URL for an object element.

Specifies the resource URL loaded by an object element. It is roughly analogous to src on several other embedding elements, but belongs specifically to object.

Family of custom data attributes for storing application-specific data on elements.

Defines custom data attributes whose names begin with data-. They allow authors to store small pieces of page-specific metadata directly on elements and access them through JavaScript, including through the dataset API.

Internet Explorer data-binding attribute identifying a field in a data source.

Was an Internet Explorer data-binding attribute that named the field to bind to. It has no role in modern standards-based HTML.

Internet Explorer data-binding attribute controlling how bound data is rendered.

Was an Internet Explorer data-binding attribute controlling how bound data was interpreted, such as text or HTML. It is proprietary and obsolete.

Internet Explorer data-binding attribute controlling records displayed per table page.

Internet Explorer data-binding attribute identifying a data source.

Was used by Internet Explorer's data binding system to identify a data source for an element. That proprietary data-binding model is obsolete.

Provides a machine-readable date or time.

Provides a machine-readable date, time, duration, or timestamp. It appears on time and can also record when content marked by ins or del was changed.

Historically declares an object without immediately instantiating it.

Historically marked an object as a declaration that should not be instantiated immediately. It was part of older object-element behavior that modern HTML no longer uses.

Hints how an image should be decoded.

Gives the browser a hint about how image decoding should relate to other page work. Values such as async and sync can influence whether decoding is allowed to happen independently or is requested before surrounding presentation continues.

Marks a text track as the default.

Marks a track element as the default timed-text track when more than one track is available. It is commonly used for a preferred subtitle, caption, or chapter track.

Defers execution of an external classic script until after parsing.

Tells the browser to download an external classic script without blocking HTML parsing and execute it after parsing is complete. Deferred scripts preserve document order relative to one another.

Specifies horizontal alignment of a fraction denominator.

Specifies the desired depth below the baseline for mpadded or related MathML layout.

Historically specifies the maximum unaccented depth of an SVG font.

Controls the diffuse reflection strength of a lighting filter.

Specifies text direction.

Sets the base direction of text for an element and its descendants. Common values are ltr, rtl, and auto, with auto allowing the browser to infer direction from the content.

Specifies text direction in SVG presentation contexts; the same name was also used by the non-standard marquee element.

Submits the text direction of an associated form control.

Causes a form submission to include the text direction of a particular input or textarea in an additional field. It is useful when the server needs both the entered text and whether the user entered it left-to-right or right-to-left.

Disables a form control or related interactive element.

Disables a form control or related interactive element so it cannot normally be used or focused. Disabled form controls are generally excluded from form submission.

Requests that Picture-in-Picture be disabled for a video element.

Requests that Picture-in-Picture controls and behavior be disabled for a video element. Browsers may still reserve some discretion over the feature.

Disables remote playback UI and capability for an audio or video element.

Prevents or discourages remote playback of media to external devices such as TVs or casting targets. It is used on audio and video where remote playback would be undesirable.

Specifies display behavior in SVG presentation contexts and selects inline or block presentation for the MathML root element.

Controls whether MathML uses display-style or compact mathematical layout.

Controls whether MathML descendants use display-style mathematical layout. Display style generally uses larger operators and roomier fraction and script placement than inline math.

Specifies the divisor applied to convolution-matrix results.

Specifies the dominant baseline used for text alignment.

Indicates that a hyperlink is intended for downloading and may suggest a filename.

Indicates that a hyperlink should be treated as a download rather than ordinary navigation when browser and security rules allow it. A value can suggest the filename to use for the downloaded resource.

Controls whether an element can be dragged.

Controls whether an element can participate as a draggable source in the HTML drag-and-drop system. It is an enumerated attribute rather than a simple boolean, so values such as true and false are meaningful.

Historically declares accepted drag-and-drop operations and data types.

Specifies the duration of an SVG animation.

Sets the simple duration of an SVG SMIL animation. It determines how long one active run of the animation lasts.

Specifies a horizontal offset or sequence of offsets.

Applies a horizontal offset in several SVG text and filter contexts. Its meaning depends on the element, such as shifting text positions or filter output.

Specifies a vertical offset or sequence of offsets.

Applies a vertical offset in several SVG text and filter contexts. Like dx, it is context-dependent.

Specifies how pixels outside an image boundary are handled by a convolution filter.

Marks an element for Element Timing performance observation.

Specifies the vertical angle of a distant light source.

Specifies how submitted form data is encoded.

Sets the encoding used for submitted form data. Common values include application/x-www-form-urlencoded, multipart/form-data for file uploads, and text/plain for limited debugging or specialized uses.

Specifies when an SVG animation ends.

Sets when an SVG SMIL animation ends. It can use clock values, event conditions, and references to other animations.

Hints the action label for the Enter key on virtual keyboards.

Hints what action label or icon a virtual keyboard should show for its Enter key. Values such as search, send, next, done, and go can make mobile input interfaces better match the control's purpose.

Historically associates a script with an event in legacy HTML.

Was historically used with script in some event-binding models to indicate which event should trigger the script. Modern HTML uses normal event listeners or event handler attributes instead.

Sets the exponent used by a gamma component-transfer function.

Exports named CSS shadow parts through a shadow tree boundary.

Exposes selected CSS shadow parts from a nested shadow tree to an outer component. It allows component authors to forward part names through multiple layers of Web Components.

Indicates whether a MathML operator should be treated as a fence.

Indicates that a MathML operator acts as a fence such as a parenthesis or bracket. Fenced operators may receive special spacing and stretching behavior.

Hints the relative fetch priority of a resource.

Provides a relative priority hint for fetching a resource. Values such as high, low, and auto let authors signal that a particular image, script, or linked resource should be treated as more or less urgent.

Sets an SVG shape's fill paint or, in animation timing, the post-animation behavior.

Sets the paint used inside an SVG shape or text element, or controls animation fill behavior on certain animation elements. Because the name is reused in different SVG contexts, its meaning depends on the element.

Sets the opacity of an SVG element's fill paint.

Determines how the interior of a shape is calculated for filling.

Applies one or more filter effects to an element.

Defines the coordinate system used by a filter region.

Sets the coordinate system used for an SVG filter region. It determines whether filter geometry is interpreted relative to the target's bounding box or in user-space coordinates.

Sets the color produced by an feFlood filter primitive.

Sets the opacity produced by an feFlood filter primitive.

Specifies the font family used to render SVG text.

Specifies the font size used to render SVG text.

Adjusts font size based on lowercase or other font metrics.

Selects a normal, condensed, or expanded font face.

Selects normal, italic, or oblique font styling.

Selects typographic variants for text.

Specifies the weight or boldness of text.

Specifies a font width selection where supported.

Legacy MathML attribute for selecting a font family; CSS is preferred.

Legacy MathML attribute for setting font size; CSS is preferred.

Legacy MathML attribute for setting font style; CSS is preferred.

Legacy MathML attribute for setting font weight; CSS is preferred.

Associates a label or output with another element by ID.

Associates one element with another by identifier. It is best known on label, where it points to a form control, and on output, where it can list controls involved in producing the result.

Associates a form-associated element with a form by ID.

Associates a form-associated element with a form elsewhere in the document by referencing the form's id. This allows controls to belong to a form even when they are not physically nested inside it.

Overrides the form submission URL for a submit control.

Overrides a form's action URL for a particular submit button or submit-type input. It allows one form to send data to different destinations depending on which submission control the user activates.

Historically specifies the format of an external font resource in SVG font markup.

Overrides form encoding for a submit control.

Overrides the parent form's submission encoding for a particular submit control. It is useful when one button needs multipart/form-data or another encoding while the rest of the form uses a different default.

Overrides the submission method for a submit control.

Overrides the parent form's HTTP submission method for a particular submit control. It is usually used to choose between get and post for different actions within the same form.

Skips constraint validation for submission through a particular control.

Lets a particular submit control bypass the form's built-in constraint validation. It is commonly used for secondary actions such as saving a draft even when required fields are incomplete.

Overrides the submission target browsing context for a submit control.

Overrides the browsing context used for the result of a form submission triggered by a particular submit control. Its values follow the same general target conventions used by links and forms.

Specifies the focal-circle radius of an SVG radial gradient.

Historically controls which outer borders of a table are rendered.

Historically controlled which outer borders of a table were drawn. CSS border properties replaced this specialized table-presentation attribute.

Historically controls whether a frame or iframe has a border.

Historically controlled whether a frame or iframe displayed a border. It was common in embed snippets for years, but CSS now controls iframe borders.

Historically sets spacing between frames.

Was a proprietary frame-layout attribute controlling space between frames. It belongs to the obsolete frameset era.

Specifies the starting value of an SVG animation.

Sets the starting value for an SVG animation. It is commonly used together with to or by.

Specifies the x-coordinate of a radial gradient's focal point.

Specifies the y-coordinate of a radial gradient's focal point.

Historically identifies the first glyph name or names in an SVG kerning pair.

Historically identifies the second glyph name or names in an SVG kerning pair.

Historically assigns one or more names to a glyph in an SVG font.

Historically controls glyph orientation for horizontal text.

Historically controls glyph orientation for vertical text.

Applies an additional transform to a gradient coordinate system.

Applies an SVG transform to the coordinate system of a gradient. It can translate, rotate, scale, or otherwise transform the gradient independently from the object using it.

Defines the coordinate system used by a gradient.

Sets the coordinate system used to interpret an SVG gradient's geometry. It switches between object-bounding-box coordinates and user-space coordinates.

Historically specifies the hanging baseline position in an SVG font.