User:Rjjiii/Alt text

Alt text is used instead of an image (or video_ in situations where it is not available to the reader, perhaps because they have turned off images in their web browser or are using a screen reader due to a visual impairment. It is part of the broader range of "alternative text" that also includes captions. The alternative text serves the same purpose and conveys the same essential information as the image. In any webpage alt text is supplied through the alt attribute. The World Wide Web Consortium (W3C) guidelines state that an image's alt attribute should convey meaning, rather than a literal description of the image itself. For example, the  attribute on an institution's logo should convey that it is the institution's logo instead of describing details of what the logo looks like.

On Wikipedia, alt text is provided in the  parameter in the MediaWiki markup. Many templates, like Infobox, have parameters for specifying alt text. For images that link to their description page (which is most images on Wikipedia), the alt attribute shout not be blank, nor should the  parameter be absent. A screen reader will default to reading out the image filename when no  attribute is available. The alt attribute must be plain text (no HTML or wiki markup such as wikilinks) without line breaks. The alt text is read by screen readers before the caption, so avoid duplicating the caption.

Captions and nearby text
Question: If the image caption provides all necessary alternative text, what should the alt attribute be?

Answer: Use minimal  text; avoid redundancy.

Images that contain words
Question: What if an image contains text?

Answer: If an image contains words important to the reader's understanding, the alternative text should contain those words.

Decorative images
Question: What if an image is purely decorative and does not convey essential meaning?

Answer: It depends on the license of the image:


 * For public domain, CC0, or similarly licensed images, unlink the image and use a blank  attribute: linkalt.
 * For CC BY-SA, GFDL, or similarly licensed images, a blank  attribute should not be used. It is Wikipedia's policy to link those images for attribution,  and linked images must have a non-blank   attribute. As concisely as possible, describe the image.

Infographics
Question: If the image is a map, diagram, infographic or other visual representation of complex data described in the article's body, what kind of information should go into the  attribute?

Answer: If a complex image is described in the body of the text, the  attribute can direct the reader to the caption, section, table, page text, or linked page.

Large amounts of data
Question: What if the image is a chart or graph containing a large amount of data not present in the article? How much data should the  attribute contain?

Answer: If possible, provide the data on the article page or a linked page.

If the data must go into the  attribute, place a summary before the data.

Glossary

 * Alternative text
 * Text that provides the same essential information as an image in an article, provided by the  attribute, image caption, and sometimes the body text.


 * Alt attribute
 * The HTML attribute used on webpages to specify alternative text to be displayed in place of an element that cannot be rendered.


 * Alt parameter
 * Wikitext markup that generates the HTML  attribute.


 * Alt text
 * Text supplied for media's  attribute or parameter.