Fixes by subject · 41 techniques
Every Technique for Images and Alt Text
Every image is either meaningful or decorative, and each needs the opposite treatment. These are the techniques for both.
Missing alt text is the second most common failure machines find on real home pages, behind low contrast. It is also the clearest case of something a machine can confirm is there and never confirm is right. A scanner sees alt="chart" and passes it. Meanwhile the chart showing sales falling 40% goes undescribed, and nothing flags it. So the techniques below cover both halves of the job. Some are about naming the images that carry meaning and hiding the ones that do not, and some are about image links, image buttons and describing a chart at the length it actually needs. The rest cover the CAPTCHA cases most people forget belong to this rule at all, and the documented ways of getting each of those wrong.
All 41 techniques
They run in technique order, and each one carries a tag. Sufficient techniques satisfy a rule. Advisory ones help without being required. Failures document a specific way of getting it wrong. None of them is mandatory, because W3C publishes techniques as documented ways of meeting a criterion rather than the only ways, so your own approach conforms as long as it meets the criterion.
- H37Sufficient1.1.1Add alt text to every meaningful image
- H67Sufficient1.1.1Give decorative images an empty alt
- G94Sufficient1.1.1Write alt text that serves the same purpose as the image
- H44Sufficient1.1.1, 1.3.1, 3.3.2, 4.1.2Attach a real label to every form field
- H30Sufficient1.1.1, 2.4.4, 2.4.9Write link text that says where the link goes
- ARIA6Sufficient1.1.1Name icon-only controls with aria-label
- H2Sufficient1.1.1, 2.4.4, 2.4.9Combine adjacent image and text links into one
- H24Sufficient1.1.1, 2.4.4, 2.4.9Add alt text to every image map area
- H36Sufficient1.1.1Add alt text to image submit buttons
- H53Sufficient1.1.1, 1.2.3, 1.2.8Give object elements meaningful fallback content
- H65Sufficient1.1.1, 1.3.1, 4.1.2Label form fields when a visible label will not fit
- H86Sufficient1.1.1Give emojis and ASCII art text alternatives
- ARIA9Sufficient1.1.1, 3.3.2Assemble one label from several text pieces
- ARIA10Sufficient1.1.1Name images and charts with aria-labelledby
- ARIA15Sufficient1.1.1Link complex images to longer descriptions
- C9Sufficient1.1.1Put decorative images in CSS backgrounds
- C18Advisory1.1.1Replace spacer images with CSS margin and padding
- F3Failure1.1.1Do not put information in CSS background images
- F13Failure1.1.1, 1.4.1Do not write alt text that drops color meaning
- F20Failure1.1.1, 4.1.2Do not let text alternatives fall out of date
- F30Failure1.1.1, 1.2.1Never use filenames or placeholders as alt text
- F38Failure1.1.1Do not leave decorative images announced
- F39Failure1.1.1Do not give decorative images junk alt text
- F65Failure1.1.1Never ship images without a text alternative
- F67Failure1.1.1, 1.2.1Do not write long descriptions that miss the point
- F71Failure1.1.1Do not fake text with look-alike characters
- F72Failure1.1.1Do not publish ASCII art without an alternative
- F89Failure2.4.4, 2.4.9, 4.1.2Do not leave image-only links without a name
- G68Sufficient1.1.1Describe the purpose of live-only streams
- G73Sufficient1.1.1Link complex images to a long description
- G74Sufficient1.1.1Describe complex images in the nearby text
- G82Sufficient1.1.1Name the function of interactive images
- G92Sufficient1.1.1Write long descriptions carrying the same information
- G95Sufficient1.1.1Give every graphic a brief text description
- G100Sufficient1.1.1Use the accepted name as the alternative
- G143Sufficient1.1.1Describe every CAPTCHA's purpose in text
- G144Sufficient1.1.1Offer a second CAPTCHA in another modality
- G196Sufficient1.1.1Describe grouped images with one alternative
- PDF1Sufficient1.1.1Add alt text to images in PDFs
- PDF4Sufficient1.1.1Hide decorative PDF images from screen readers
- PDF13Sufficient2.4.4, 2.4.9Replace raw URLs in PDFs with descriptive text
More on Images and alt text
The other 13 subjects
Knowing the technique is not the same as knowing you need it.
The free scan checks 10 pages in a real browser and maps every machine-checkable failure to the exact fix guide that clears it.