Accessibility & Standards
Accessibility is the part of publishing that is easiest to skip and hardest to retrofit, and generated code makes it worse by producing styled divs where a real button belonged. This category gives the practical vocabulary with real numbers: the 4.5:1 contrast ratio WCAG asks for on normal text, what an empty alt attribute means and when to use one, why the first rule of ARIA is not to use ARIA, and what a screen reader does with a heading structure that skips from h1 to h4. It also covers accessible and tagged PDFs, which matter because a PDF is among the most-published file types and a scanned one is completely opaque, and the standards and legislation now involved — WCAG 2.2, EN 301 549, VPATs, the European Accessibility Act and ADA compliance. General information throughout, not legal advice.
33 terms in this category
Accessibility Audit
An accessibility audit is a structured review of a site or document against a named standard, producing a list of failures mapped to specific success criteria. It combines automated scanning with manual testing, because tools alone catch only part of the picture.
Accessible Name
The accessible name is the short string that identifies an element to assistive technology — the words a screen reader speaks when focus lands on a link, button or field. Browsers work it out from several possible sources in a fixed order.
Accessible PDF
An accessible PDF is one that assistive technology can read out in a sensible order, because it carries a hidden structure of tags alongside the visible page. A scanned page saved as a PDF is a picture of text and carries none of that.
ADA Compliance
ADA compliance refers to meeting the Americans with Disabilities Act as it has been applied to websites and digital services. The statute names no web standard, so the picture is built from regulation and case law rather than from a single document.
Alt Text
Alt text is the alt attribute on an HTML image: a short written replacement for the picture, read aloud by a screen reader and shown when the image fails to load. A decorative image takes an empty alt, not a missing one.
ARIA Label
aria-label is an attribute that gives an element an accessible name in words, for the cases where no visible text can do it. The first rule of ARIA is not to use ARIA: if a native HTML element already does the job, use that instead.
Captions
Captions are time-synchronised text for a video's audio: the dialogue, who is speaking, and any sound that carries meaning. They are not subtitles, which assume the viewer can hear and only translate the words.
Colour Contrast
Colour contrast is the difference in luminance between text and the surface behind it. WCAG asks for at least 4.5:1 for normal text and 3:1 for large text at Level AA.
Contrast Ratio
A contrast ratio is a single number between 1:1 and 21:1 describing how far apart two colours are in relative luminance. It is what a contrast checker reports, and it is calculated rather than estimated.
Document Outline
A document outline is the nested hierarchy a page's headings describe — its table of contents, implied rather than printed. Assistive technology builds navigation directly from it.
EN 301 549
EN 301 549 is the European standard setting accessibility requirements for ICT products and services, and it is what public-sector procurement across the EU points at. For web content it adopts WCAG wholesale rather than inventing its own rules.
European Accessibility Act
The European Accessibility Act is EU legislation that extends accessibility requirements from the public sector to a defined list of products and services sold to consumers in the EU. It has applied since 28 June 2025.
Focus Indicator
A focus indicator is the visible ring or outline showing which element the keyboard is currently on. Switching it off with an outline of none and putting nothing back is one of the most common faults in hand-written CSS.
Form Label
A form label is the visible text tied programmatically to an input, so that software as well as sighted readers knows what belongs in the box. In HTML it is a label element linked to the field by id.
Keyboard Navigation
Keyboard navigation is operating a page without a mouse: Tab and Shift+Tab to move between controls, Enter and Space to activate them, arrow keys inside composite widgets such as menus and radio groups.
Landmark Region
A landmark region is a section of a page with an announced role — banner, navigation, main, complementary, contentinfo — that a screen reader user can jump straight to instead of reading through everything above it.
Language Attribute
The language attribute declares what human language a page or a passage is written in, using lang on an HTML element. It tells software how to pronounce the words, which most readers never notice until it is wrong.
Live Region
A live region is a part of the page marked so that assistive technology announces changes to it without moving focus. It is how a reader hears 'Upload complete' when nothing they did caused it to appear.
Plain Language
Plain language means writing so that the people you are writing for can find what they need, understand it the first time, and act on it. It is a property of the reader's experience, not a reading-score target.
Reading Order
Reading order is the sequence in which content is presented to assistive technology — the source order of the HTML, or the tag tree of a PDF. When it disagrees with the visual order, the page stops making sense out loud.
Reduced Motion
Reduced motion is a setting people switch on at the operating system level to cut down animation, and a CSS media query that lets a page respect it. Honouring it takes a handful of lines.
Screen Reader
A screen reader is software that turns what is on screen into speech or braille and gives the user a keyboard interface for moving through it. JAWS, NVDA, VoiceOver, Narrator and TalkBack are the ones in common use.
Semantic HTML
Semantic HTML means using the element that matches the meaning of the content — button, nav, h2, label, table — rather than styling a generic div or span to look the part.
Skip Link
A skip link is a link at the very top of a page that jumps past the header and navigation straight to the main content. It is normally hidden until it receives keyboard focus, then appears.
Tab Order
Tab order is the sequence in which pressing Tab moves focus through a page's interactive elements. By default it follows the order those elements appear in the HTML source.
Tagged PDF
A tagged PDF carries a hidden tree of structure elements — headings, paragraphs, lists, tables, figures — running in parallel with the visible page. Tags are what let software tell a heading from a caption.
Target Size
Target size is how big a clickable or tappable area is, measured in CSS pixels. WCAG 2.2 sets a minimum of 24 by 24 at level AA, with a more generous 44 by 44 at level AAA.
Text Alternative
A text alternative is text that serves the same purpose as non-text content — an image, an icon, a chart, a map, an audio clip, a video. It is the principle that alt text, captions and transcripts each implement.
Text Resize
Text resize is the ability to enlarge the words on a page without losing content or breaking the layout. WCAG sets the bar at 200 per cent, and a related criterion pushes it effectively to 400 per cent.
Transcript
A transcript is the full text of an audio or video recording, written out as a document rather than tied to the timeline. For audio-only content it is the text alternative; for video, a descriptive transcript also covers what is shown on screen.
VPAT
A VPAT, or Voluntary Product Accessibility Template, is the form a vendor fills in to describe how far a product meets a named accessibility standard. The completed document is properly called an Accessibility Conformance Report.
WCAG
WCAG, the Web Content Accessibility Guidelines, is the W3C standard that defines what accessible web content is. Its success criteria at Levels A, AA and AAA are what accessibility law and procurement point to.
Web Accessibility
Web accessibility is the practice of building pages, documents and media that people with disabilities can perceive, operate and understand — including people using a screen reader, a keyboard alone, screen magnification or captions.