A text alternative is the standard's own term for text attached to something that is not text, in a way software can follow from one to the other. It can be the words themselves, the way alt text sits on a photograph. It can also be a short string pointing at a longer description elsewhere. A chart carries a few words saying that a description follows, and the description itself is written out in the paragraph underneath. What the alternative has to achieve comes from the rule rather than from the definition, and the rule asks for text that serves the equivalent purpose. That is the test to apply. Not what the thing looks like, but what it was there to give the reader.
In practice
The phrase reaches a long way past images. A transcript is the text alternative for audio. Captions are one for a video's dialogue. The accessible name is one for a control drawn as an icon. Thinking in these terms rather than in terms of alt text stops the commonest mistake, which is describing what a thing looks like instead of saying what it does. For a chart drawn to make one point, the alternative is that point rather than the words "bar chart". For a chart somebody is meant to read numbers out of, the point is not enough and the numbers have to be reachable in text somewhere.
The term reaches all of those and the obligations do not all come from the same rule, which is a distinction worth having before somebody tells you one rule covers your whole video library. Under the non-text content rule, a video needs only enough text to identify what it is. The captions, the transcript and the audio description come from the time-based media guideline instead, each at its own level.
One category catches people out. Things made of characters can still be non-text content, because text here means characters expressing something in a human language. ASCII art, emoticons, leetspeak and an image of a word are all outside that, and all of them need alternatives. Three cases ask for nothing but a way to skip. Pure decoration, anything there only for visual formatting, and anything not presented to users at all. A fourth group asks for less than a full alternative rather than none. A test, a sensory experience, a CAPTCHA. Those need text saying what the thing is, because writing out the answer would destroy the point of it.
Why it matters
Text is the one format that can become anything else, and that is the whole reason the standard leans on it so hard. It can be read aloud by a screen reader, enlarged for somebody with low vision, or pushed out to a braille display. It can be translated, restyled by a reader who needs wider spacing, or turned into symbols and simpler language. Nothing else on your page does all six. So every time something is not text, the only question that matters is what route back to text you left, and the answer that locks people out is none.
Where people get it wrong
An infographic carrying the alt text "infographic showing our process" has been labeled rather than replaced. The alternative for an infographic is the process, written out. If it is too long to sit in an attribute, the definition already allows for that. Put a short string on the image saying a description follows, then write the description into the page underneath, where everybody gets to read it.
Where this shows up on the site
Related terms
- Alt textAlt text is the written description attached to an image, and it is what a screen reader reads out in place of the picture.
- Decorative imageA decorative image is one that serves only an aesthetic purpose, carries no information, and does no work.
- TranscriptA transcript is the text version of audio or video, and two different things go by that one word.
- CaptionsCaptions are a synchronized text version of everything you would hear in a video, covering speech and the non-speech sound that matters as well.
- Accessible nameThe accessible name is what assistive technology announces an element as, the words a screen reader speaks when it lands on a button or a link.
Knowing the word is the easy part.
Find out where your own site stands. The free scan checks 10 pages in a real browser against all 90 supported automated rules, separates 27 best-practice checks from its WCAG findings, and names the rule behind every result.