Semantic HTML

Designing so that people with disabilities can use a thing, and the standards that make it checkable.

Checking that people using screen readers, keyboards, magnification, or other assistive technology can actually use an interface, through a mix of automated scans and hands-on testing.

A stack of headings that each expand to reveal a section of content, saving space on long pages and small screens at the cost of hiding what readers might have needed to see.

Attributes that describe roles, states, and relationships to assistive technology when HTML cannot.

The short row of links near the top of a page that shows where it sits in a site's hierarchy, such as Home › Shoes › Running, letting people orient themselves and step back up a level in one click.

Rows and columns of values designed for looking things up and comparing exact figures, which read best with right-aligned numbers, light rules, and headers that stay put, and remain one of the hardest components to make work on a phone.

An interface that exists inside the fiction, readable by the character as well as the player.

The live tree of objects a browser builds from a document, and the surface every UI framework writes to.

Deliberately controlling which element receives keyboard focus as an interface changes.

Confining keyboard focus inside a modal surface so it cannot wander behind it.

A component supplying behavior and accessibility with no styling of its own.

The markup language every web page is written in, invented at CERN around 1990 as a simple way to tag documents and link them, and grown by thirty years of browser competition into an application platform.

Making every interactive affordance reachable and operable without a pointer.

A window that blocks the rest of the interface until it is dealt with, useful for decisions that truly demand attention and overused for almost everything else.

Building so the core experience works without scripts, with richer behavior layered on top.

A syndication format letting readers subscribe to a site without an intermediary.

Software that turns an interface into speech or braille for people who can't see the screen, which navigates by structure rather than reading top to bottom, and exposes every shortcut a sighted design took.

Making content discoverable through search, most of which is ordinary quality work.

Machine-readable markup describing what a page is about, in a shared vocabulary.

An on-screen control for a single on-or-off setting that takes effect immediately, borrowed from light switches, distinct from checkboxes and radio buttons, and notorious for leaving people unsure which state it is in.

The small set of typed components through which all interface markup is expressed.

Arranging elements so their visual weight matches their importance, telling the eye where to look first, second, and last.

The 1998 tag-based format for structured documents and data that once carried almost everything on the web and still underlies office files, feeds, and SVG, along with a set of well-known parser attacks.