Attribute
A name and optional value attached to an HTML element to provide additional information.
Cascade
The process that chooses between competing CSS declarations.
Canonical URL
The preferred URL identified for a page, used as a signal rather than an indexing guarantee.
DOM
The browser’s object representation of the parsed document.
Element
A unit of an HTML document, such as a heading, paragraph or link.
Event
A notification of an occurrence such as a click or input change.
HTTP status
A response code describing the outcome of an HTTP request.
Landmark
A meaningful page region, such as main content or navigation.
Origin
A combination of scheme, hostname and port used in browser security boundaries.
Progressive enhancement
Starting with a working baseline and adding capabilities when the browser can support them.
Selector
A pattern used to match elements, commonly for CSS styling or DOM queries.
Semantic HTML
HTML chosen to express meaning rather than only appearance.
Static website
A website that delivers prepared files; those files may have been generated during a build.
Viewport
The area in which a document is displayed. Its size affects responsive layout.

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