HTML glossary

367 HTML terms, from Novice to Master. Start with the basics or jump to a level.

Updated October 16, 2026

Novice

<b>: The element that draws attention to text without adding importance or emphasis.
<body>: The element that contains the document content presented as the web page.
<br>: The element that creates a line break where the break is part of the content.
<div>: A generic container for flow content when no more meaningful element fits.
<em>: The element that marks stress emphasis that can change a sentence's meaning.
<figcaption>: The element that provides a caption for its parent figure.
<figure>: The element that groups self-contained content that may have a caption.
<head>: The element that contains document metadata rather than the page's main visible content.
<hr>: The element that represents a thematic break between groups of content.
<html>: The root element that contains the head and body of an HTML document.
<i>: The element that marks text in an alternate voice or otherwise offset from normal prose.
<p>: The element that represents a paragraph.
<span>: A generic inline container for phrasing content when no more meaningful element fits.
<strong>: The element that marks content as strongly important, serious, or urgent.
<title>: The element that gives a document the title shown in browser tabs and other interfaces.
Alternative text: Text that communicates an image's purpose when the image cannot or should not be viewed.
Anchor element: The a element, which creates a hyperlink when it has an href attribute.
Attribute: A name, sometimes paired with a value, that adds information or behavior to an element.
Attribute value: The data assigned to an HTML attribute.
Boolean attribute: An attribute whose presence means true and whose absence means false.
Character reference: HTML syntax that represents a character using a named or numeric reference.
Child element: An element directly contained by another element.
class attribute: An attribute that contains one or more CSS classes.
Description details: A description, definition, or value associated with a term in a description list.
Description list: A list of terms or names paired with descriptions, definitions, or values.
Description term: A term or name being described inside a description list.
Document type declaration: The declaration at the start of a document that tells browsers to use modern HTML parsing.
Element: A part of an HTML document represented by a tag and, when allowed, its content.
Element content: The text and elements placed between an element's start and end tags.
End tag: The tag that closes an HTML element, written with a slash before the tag name.
Fragment identifier: The portion of a URL that appears after the # symbol.
Global attribute: An attribute that can be used on every HTML element, subject to the attribute's rules.
Heading: A title that introduces a page or section of content.
Heading element: One of the h1 through h6 elements used to identify headings at different levels.
height attribute: An attribute that supplies an element's intended height in CSS pixels.
href: The attribute that supplies a hyperlink's destination URL.
HTML: The markup language used to give web content its structure and meaning.
HTML comment: Text in HTML source that browsers do not display as page content.
HTML document: A text document containing HTML markup that a browser can parse into a web page.
HTML source: The original HTML text sent to or opened by a browser.
HTML validation: Checking markup against HTML's conformance rules to find mistakes.
Hyperlink: A connection that a user can follow to another resource or location.
ID: A document-wide identifier assigned to a single element.
Image element: The img element, which embeds an image in a document.
Link element: This loads an external stylesheet.
List item: One entry inside an ordered, unordered, or menu list.
Markup language: A language that adds labels to describe the content so that software can understand its structure and meaning.
Named character reference: A character reference that uses a standard name, such as amp for an ampersand.
Nesting: Placing one HTML element inside another element.
Numeric character reference: A character reference that identifies a Unicode character by number.
Ordered list: A list whose item order is meaningful.
Parent element: An element that directly contains another element.
Sibling element: An element that shares the same parent as another element.
src: The attribute that gives the URL of an embedded resource such as an image or script.
Start tag: The tag that opens an HTML element and can contain its attributes.
Style element: Embeds CSS directly in an HTML page.
Tag: Markup enclosed in angle brackets that begins or ends an HTML element.
title attribute: A global attribute that provides advisory information about an element.
Unordered list: A list whose item order does not change the meaning.
Void element: An HTML element that cannot contain child content and has no end tag.
Whitespace: Spaces, tabs, and line breaks used to separate text or make source easier to read.
width attribute: An attribute that supplies an element's intended width in CSS pixels.

Apprentice

<abbr>: The element for an abbreviation or acronym, optionally with its expansion in a title attribute.
<address>: The element for contact information associated with an article or the document.
<article>: The element for self-contained content that could be reused or distributed independently.
<aside>: The element for content indirectly related to the surrounding content.
<blockquote>: The element for a section quoted from another source.
<button>: The element for a button that can submit, reset, or perform a scripted action.
<caption>: The element that provides a title or explanation for its table.
<cite>: The element for the title of a creative work.
<code>: The element for a fragment of computer code.
<col>: The element that represents one or more columns within a colgroup.
<colgroup>: The element that represents a group of columns in a table.
<fieldset>: The element that groups related form controls and labels.
<footer>: The element for footer information belonging to its nearest section or the page.
<header>: The element for introductory or navigational content belonging to a page or section.
<input>: The element that creates a data-entry control selected by its type attribute.
<kbd>: The element for user input, commonly keyboard input.
<label>: The element that provides a caption for a form control.
<legend>: The element that captions a fieldset.
<main>: The element for the document body's dominant, unique content.
<mark>: The element for text highlighted because it is relevant in the current context.
<nav>: The element for a major group of navigation links.
<optgroup>: The element that groups related options inside a select control.
<option>: The element representing one choice in a select control or datalist.
<pre>: The element for preformatted text whose whitespace is significant.
<q>: The element for a short quotation that stays within surrounding text.
<s>: The element for content that is no longer accurate or relevant.
<samp>: The element for sample output from a program or computing system.
<script>: The element that embeds or references code to be executed in the browser.
<search>: The element for controls used to search or filter content.
<section>: The element for a standalone thematic section that normally has a heading.
<select>: The element that lets a user choose from a list of options.
<small>: The element for side comments such as copyright text or legal fine print.
<sub>: The element for subscript text required by typographic convention.
<sup>: The element for superscript text required by typographic convention.
<tbody>: The element that groups a table's main rows.
<textarea>: The element for editing a multi-line plain-text value.
<tfoot>: The element that groups a table's summary or footer rows.
<thead>: The element that groups a table's header rows.
<time>: The element for a date, time, duration, or machine-readable date-time value.
<u>: The element for text with a non-textual annotation, such as a spelling mark.
<var>: The element for a variable or placeholder in a mathematical or programming expression.
Ancestor: An ancestor is a programming term when dealing with hierarchical documents, such as HTML…
autocomplete: An attribute that provides guidance for automatically filling a form control.
autofocus: A Boolean attribute requesting focus for an element when its document or dialog becomes active.
Checkbox: An input control representing an independently selected on-or-off choice.
checked: A Boolean attribute that sets the initial selected state of a checkbox or radio button.
Color input: An input control for choosing a color.
colspan: The number of columns a table cell spans.
Constraint validation: The browser process that checks whether supported form controls meet their declared rules.
Data table: A table that represents relationships between data arranged in rows and columns.
Date input: An input control for a calendar date without a time zone.
disabled: A Boolean attribute that makes a control unavailable and normally excludes it from submission.
Document outline: The hierarchy of sections and headings that organizes a document's content.
Email input: An input control that expects one or more email addresses.
File input: An input control that lets a user choose files for submission.
for attribute: The label attribute whose value matches the id of the control it labels.
Form: A section containing controls that collect information for submission.
Form action: The URL that receives a submitted form's data.
Form control name: The name used as a key for a control's value in submitted form data.
Form control value: The data currently held by a form control.
Form encoding type: The format used to encode form data for a POST submission.
Form method: The HTTP method or dialog behavior used when a form is submitted.
GET form: A form submission that encodes form data into the URL's query.
Heading hierarchy: The ordered heading levels that communicate how page sections relate.
Hidden input: A non-visible input that contributes a name and value during form submission.
Image input: A graphical submit button whose value includes the selected image coordinates.
Input type: The input attribute value that determines the control's data and behavior.
Landmark: A meaningful page region that helps users and assistive technology navigate the document.
Local date and time input: An input control for a date and time without a time-zone value.
max: The highest valid value accepted by a supported form control.
maxlength: The maximum number of characters a user can enter into a supported control.
min: The lowest valid value accepted by a supported form control.
minlength: The minimum number of characters required for a valid user-entered value.
Month input: An input control for a year and month.
multiple: A Boolean attribute that allows more than one value where the control supports it.
Number input: An input control for a numerical value.
Password input: A text input that visually obscures its value while it is entered.
pattern: A regular expression that a supported text control's complete value must match.
placeholder: A short hint displayed inside an empty text-like control.
POST form submission: A form submission that sends form data in the request body.
Radio button: An input control representing one choice from a group sharing the same name.
Range input: An input control for selecting an approximate number within a range.
readonly: A Boolean attribute that prevents editing while keeping the control usable and submittable.
Replaced element: An element like img or video whose content comes from outside CSS.
required: A Boolean attribute that requires a control to have a valid value before submission.
Reset button: A button that restores form controls to their initial values.
rowspan: The number of rows a table cell spans.
scope attribute: An attribute that states which row, column, or group a header cell applies to.
Search input: A text input intended for search terms.
selected: A Boolean attribute that sets an option as initially selected.
Semantic HTML: Using HTML elements whose names defined their purpose, rather than generic counterparts.
step: The allowed value interval for a supported numeric, date, or time control.
Submit button: A button that starts submission of its associated form.
Table data cell: A cell containing table data.
Table header cell: A cell that labels a row, column, or group of cells.
Table row: A horizontal group of header and data cells.
Telephone input: An input control intended for a telephone number.
Text input: A single-line input control for ordinary text.
Time input: An input control for a time of day without a time zone.
URL input: An input control that expects an absolute URL.
Validity state: The set of results describing why a form control's value is valid or invalid.
Week input: An input control for a numbered week of a year.

Journeyman

_blank target: A target keyword requesting a new top-level browsing context, commonly a new tab.
<area>: The element that defines one clickable region and destination in an image map.
<audio>: The element that embeds sound content and can provide browser playback controls.
<base>: The element that sets the base URL used to resolve relative URLs in a document.
<bdi>: The element that isolates text whose direction may differ from its surroundings.
<bdo>: The element that overrides the normal bidirectional ordering of its text.
<canvas>: The element that provides a bitmap drawing surface normally controlled through scripting.
<details>: The element that contains additional information a user can reveal or hide.
<dialog>: The element that represents a dialog box or other temporary interactive component.
<embed>: The element that embeds external content handled by the browser or a supported plugin.
<iframe>: The element that embeds another HTML page as a nested browsing context.
<link>: The element that declares a relationship between the document and another resource.
<map>: The element that defines a collection of interactive areas for an image map.
<meta>: The element for metadata that cannot be expressed by title, base, link, style, or script.
<noscript>: The element that provides alternate HTML when scripting is disabled or unsupported.
<object>: The element that embeds an external resource and can contain fallback content.
<picture>: The element that offers image sources for responsive selection before a required img element.
<rp>: The element providing fallback parentheses for browsers that do not render ruby annotations.
<rt>: The element containing ruby pronunciation or annotation text.
<ruby>: The element that groups base text with its ruby annotations.
<source>: The element that supplies an alternative media or image resource for its parent.
<summary>: The element that provides the visible label or summary for its parent details element.
<track>: The element that adds timed text data, such as captions, to audio or video.
<video>: The element that embeds video content and can provide browser playback controls.
<wbr>: The element that marks a place where a browser may break a line if needed.
Accessible name: The text assistive technology uses to identify an interface element.
accesskey: A global attribute suggesting a keyboard shortcut for activating or focusing an element.
ARIA role: A role that communicates an element's purpose to accessibility tools when native semantics are insufficient.
aria-describedby: An ARIA attribute that identifies elements providing an accessible description.
aria-hidden: An ARIA attribute that removes an element and its descendants from the accessibility tree when true.
aria-label: An ARIA attribute that supplies an accessible name as a text value.
aria-labelledby: An ARIA attribute that uses other elements' text to form an accessible name.
Art direction: Providing differently composed or cropped images for different presentation conditions.
autoplay: A Boolean attribute requesting that media start playing as soon as allowed.
Bidirectional isolation: Keeping one text segment's direction from unexpectedly affecting surrounding bidirectional text.
Canonical link: A link identifying the preferred URL for content available through multiple URLs.
Captions track: A text track containing dialogue and relevant sound information for people who cannot hear the audio.
Character encoding declaration: Markup near the start of a document that declares its text encoding as UTF-8.
contenteditable: A global attribute indicating whether the user can edit an element's content.
Custom data attribute: An attribute beginning with data- that stores page-specific data on an element.
defer: A Boolean classic-script attribute that delays execution until parsing finishes while preserving document order.
dir attribute: The attribute that sets left-to-right, right-to-left, or automatically determined text direction.
Document language: The primary human language of a document or element's text.
Document metadata: Information about a document, such as its title, encoding, language, and related resources.
draggable: A global attribute indicating whether an element can be dragged through native drag and drop.
External script: A script loaded from a separate resource through a script element's src attribute.
Favicon: An icon associated with a website or page for browser tabs, bookmarks, and similar interfaces.
hidden: A global attribute indicating that an element is not currently relevant and should not be presented.
Image candidate: One image resource the browser may choose from a responsive image source set.
Image map: An image with defined regions that link to different destinations.
Inline script: Script code written directly inside a script element.
lang attribute: The attribute that declares the human language of an element's content.
Lazy loading: Delaying an off-screen resource until it is likely to be needed.
Left-to-right text: Text whose main reading direction proceeds from left to right.
Link relationship: A keyword describing how the current document and a linked resource are related.
loading attribute: An attribute that hints whether an image or iframe should load immediately or lazily.
loop: A Boolean attribute that makes media begin again after it finishes.
Media controls: Browser-provided controls for playing, pausing, seeking, and adjusting media.
Meta content: The value supplied for a named piece of metadata.
Meta description: A short document summary supplied as metadata, often used by search and sharing tools.
Meta name: The name identifying which document-level metadata a meta element supplies.
Module script: A script processed as a JavaScript module with imports, strict mode, and module scoping.
muted: A Boolean attribute that initially silences an audio or video element.
noopener: A link relationship that prevents a newly opened page from receiving an opener reference.
noreferrer: A link relationship that omits referrer information and also prevents an opener relationship.
open attribute: A Boolean attribute that makes a details element expanded or a dialog displayed.
Pixel density descriptor: A srcset descriptor stating an image resource's intended pixel-density scale.
preload: A media attribute that hints how much content the browser should load before playback.
rel attribute: The attribute containing one or more link relationship keywords.
Responsive image: An image setup that lets the browser select a suitable resource for the display and layout.
Right-to-left text: Text whose main reading direction proceeds from right to left.
Ruby annotation: Small pronunciation or explanatory text shown with East Asian base text.
sizes: An attribute describing an image's expected rendered width under different conditions.
spellcheck: A global attribute that hints whether editable text should receive spelling and grammar checking.
srcset: An attribute listing image candidates with width or pixel-density descriptors.
style attribute: A global attribute containing CSS declarations applied directly to one element.
Stylesheet link: A link element that loads an external CSS stylesheet.
Subtitles track: A text track translating or transcribing dialogue for viewers who can hear but may not understand it.
tabindex: A global attribute that controls whether and where an element participates in sequential focus navigation.
target attribute: An attribute that names where a linked or submitted document should open.
Text direction: The direction in which text and inline content progress.
Text track: Time-based text or metadata associated with audio or video.
translate: A global attribute indicating whether an element's text and translatable attribute values should be translated.
usemap: The attribute that connects an image to a map element by fragment identifier.
Video poster: An image displayed in a video element before video frames are available.
Viewport metadata: Metadata that guides how a page's viewport is sized and scaled on mobile devices.
Width descriptor: A srcset descriptor stating an image resource's intrinsic width in pixels.

Freelancer

<datalist>: The element that supplies suggested options to an associated input without limiting entry to those options.
<meter>: The element that displays a measured value within a known range.
<output>: The element that represents the result of a calculation or user action.
<progress>: The element that displays completion progress for a task.
<slot>: The element that marks where assigned light-DOM content appears inside a shadow tree.
<template>: The element that stores inert HTML fragments for later use.
accept attribute: A file-input attribute that hints which file types the user should select.
allow attribute: An iframe attribute that controls which Permissions Policy features its content may use.
Auto popover: A popover mode with light dismissal that normally closes other auto popovers.
Autonomous custom element: A custom element with its own hyphenated tag name.
capture attribute: A file-input attribute that hints a preferred camera or microphone source for new media.
crossorigin: An attribute that configures a cross-origin request and whether credentials are included.
Custom element: An author-defined HTML element whose behavior is registered through the Custom Elements API.
Customized built-in element: A custom element that extends a built-in HTML element and uses the is attribute.
Declarative shadow DOM: HTML syntax that creates a shadow root from a template element during parsing.
download attribute: An anchor or area attribute that requests a download and can suggest a filename.
Download link: A hyperlink that suggests downloading its destination instead of navigating to it.
enterkeyhint: A global attribute that hints which action label or icon to show on a virtual enter key.
exportparts: An attribute that exposes selected part names from a nested shadow tree through its host.
Focusable area: A page region or control that can become the target of keyboard focus.
form attribute: An attribute that associates a form control with a form by id, even when it is outside that form.
Form data set: The ordered name-and-value entries constructed from a form for submission.
Form owner: The form element associated with a form control or other form-associated element.
Form submission: The process of constructing form data and sending or navigating it to the form's destination.
Form-associated element: An element with form-related behavior that can be connected to a form owner.
Hint popover: A popover mode for transient hints that can coexist with an auto popover.
Iframe sandbox: Restrictions applied to content in an iframe through its sandbox attribute.
Implicit submission: Form submission triggered by an action such as pressing Enter in a text control.
inert: A global attribute that prevents an element and its descendants from receiving focus or user interaction.
inputmode: A global attribute that hints which input interface, such as a numeric keyboard, would be useful.
integrity attribute: An attribute containing hashes used to verify a fetched script or stylesheet.
itemid: An attribute giving a typed microdata item a global identifier.
itemprop: An attribute that assigns one or more property names to data in an element.
itemref: An attribute that adds properties from elements outside a microdata item's descendants.
itemscope: A Boolean attribute that creates a new microdata item.
itemtype: An attribute containing vocabulary URLs that define a microdata item's type.
Light dismiss: Closing a temporary interface by interacting outside it or making a platform close request.
list attribute: The input attribute whose value identifies a datalist containing suggestions.
Manual popover: A popover mode that remains open until explicitly hidden.
Microdata: HTML attributes that add machine-readable items and name-value properties to document content.
Microdata item: A group of microdata properties describing one thing.
Modal dialog: A dialog that makes the rest of its document inert until the dialog closes.
Multipart form data: A form encoding that separates entries into parts and supports file uploads.
Named slot: A slot identified by name so matching host children can be assigned to it.
nonce attribute: A one-use token that a Content Security Policy can require on allowed inline script or style elements.
Non-modal dialog: A displayed dialog that allows interaction with the rest of the document.
part attribute: An attribute naming parts inside a shadow tree so external CSS can select them.
ping attribute: An anchor or area attribute listing URLs to notify when the hyperlink is followed.
Ping URL: A URL notified when a user follows a hyperlink, when hyperlink auditing is enabled.
Popover: An element displayed in the top layer using built-in showing, hiding, and dismissal behavior.
popover attribute: A global attribute that turns an element into a popover.
Popover target: A popover element connected to a button or input that can show or hide it.
referrerpolicy: An attribute that controls which referrer information is sent when fetching or navigating.
Sequential focus navigation: Moving focus through eligible page controls in an ordered sequence, commonly with the Tab key.
Shadow host: An element to which a shadow root is attached.
Shadow root: A document fragment that forms the root of a component's encapsulated shadow tree.
shadowrootmode: A template attribute that requests an open or closed declarative shadow root.
Slot assignment: The process that matches a shadow host's children with slots in its shadow tree.
srcdoc: An iframe attribute containing the HTML document that should be embedded directly.
Subresource integrity: A security feature that checks a fetched resource against an expected cryptographic hash.
Successful control: A form control that contributes its name and value to submitted form data.
Template contents: The separate document fragment containing the child markup of a template element.
URL-encoded form data: A form encoding that represents name-and-value pairs using URL-style escaping.

Master

Adoption agency algorithm: The tree-construction procedure that repairs certain misnested formatting elements.
Character token: A parser token representing one or more characters of document text.
Comment node: A DOM node containing the text of an HTML comment.
Comment token: A parser token representing an HTML comment.
Content category: A named group of HTML elements that share roles used by content-model rules.
Content model: The rule describing which kinds of child content an HTML element may contain.
Context element: The element whose type and state guide how an HTML fragment is parsed.
Custom element content model: The rules governing which children are valid in an author-defined custom element.
Data state: The tokenizer's normal state for reading document text and recognizing markup.
Document node: The DOM node representing the whole document and serving as the tree's root.
DOM tree: The in-memory tree of document, element, text, comment, and other nodes produced from HTML.
Element node: A DOM node representing an element and its attributes.
Embedded content: Content that imports or draws another resource, such as an image, video, iframe, or canvas.
End-of-file token: The token indicating that no more input remains for the parser.
Flow content: The broad category containing most elements allowed in a document body.
Foreign content: SVG or MathML content parsed within an HTML document under its own namespace rules.
Foster parenting: Parser behavior that relocates certain misplaced table content outside the table structure.
Heading content: The h1 through h6 and hgroup elements used to identify section headings.
HTML conformance checker: A tool that reports whether markup follows the requirements placed on HTML authors.
HTML fragment parsing: Parsing an HTML string as a fragment using a supplied element as its context.
HTML namespace: The namespace URI that identifies ordinary HTML elements in the DOM.
HTML parser: The browser component that turns HTML source into a document tree.
HTML serialization: Converting a document or node tree back into HTML text.
HTML tokenization: The parsing stage that converts input characters into tags, text, comments, and end-of-file tokens.
Implied end tag: An end tag the parser acts as though it encountered when certain later markup makes it unnecessary.
Insertion mode: The parser state that selects tree-construction rules based on the current document context.
Integration point: A location in SVG or MathML where the parser can switch between foreign-content and HTML parsing rules.
Interactive content: Elements specifically intended for user interaction, such as links and form controls.
List of active formatting elements: Parser state used to reconstruct and repair formatting elements across misnested markup.
MathML namespace: The namespace URI that identifies inline MathML elements in a document tree.
Metadata content: Elements that set presentation, behavior, relationships, or other information about a document.
Node document order: The order nodes appear when a document tree is traversed from beginning to end.
Obsolete feature: An old HTML feature that current documents should not use.
Optional tag: A start or end tag that HTML syntax permits an author to omit under specific conditions.
Palpable content: Content expected to contribute something users can perceive rather than existing only as structure.
Parse error: HTML input that violates a parsing rule but is still handled through defined recovery behavior.
Parser error recovery: The standardized rules browsers follow to build a predictable document tree from malformed HTML.
Parser-blocking script: A script whose fetching or execution pauses further HTML parsing.
Parser-inserted script: A script element created by the HTML parser rather than by a DOM operation.
Phrasing content: Elements and text used within paragraphs and other runs of text.
RAWTEXT state: A tokenizer state that treats content as text until the matching end tag, while recognizing no character references.
RCDATA state: A tokenizer state that treats content as text but still recognizes character references and the matching end tag.
Script preparation: The HTML processing steps that determine a script's type, source, readiness, and execution behavior.
Script-supporting element: An element used to support scripts without directly representing page content, such as script or template.
Sectioning content: Elements that create major thematic sections, including article, aside, nav, and section.
Stack of open elements: The parser's ordered list of elements that have started but have not yet been fully closed.
SVG namespace: The namespace URI that identifies inline SVG elements in a document tree.
Tag token: A parser token representing a start tag or end tag and its parsed attributes.
text/html MIME type: The media type that identifies a resource as an HTML document parsed with HTML syntax.
Tokenizer state: The current rule set the HTML tokenizer uses to interpret the next input characters.
Transparent content model: A content model that largely adopts the content rules of the element's surrounding context.
Tree construction: The parsing stage that uses tokens to create and arrange nodes in the document tree.
XHTML syntax: XML syntax used to represent HTML elements under XML parsing rules.

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