Images have appropriate alternative text

From WolfWikis

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Explanation

All images must have a textual description with them that tell the function of the image. This ensures that people with visual disabilities can get the same message from your page as a sighted user.

Procedure

There are three types of alternate text.

Alt Attribute

This is for brief descriptions of images. Usually the description is no longer than 10 -15 words. It is stored in the alt attribute of the <img> tag. For example, a photo of an instructor would look like:

<img src="photo.jpg" alt="Dr. Knowitall">

It is not necessary to type "an image of Dr. Knowitall". One thing to keep in mind is that screen readers are forced to read everything you type in the alt attribute.

Long Description

These are for longer descriptions of images and the description is stored in an external file. An example of a long description is:

<img src="photo.jpg" alt="" longdesc="photo_description.html">

where photo_description.html would hold a the description of the image. Screen readers have the option of reading these descriptions.

Null String

From a coding perspective null strings look identical to alt attributes. The difference is you don't tyoe anything in the alt attribute. For example,

<img src="background.jpg" alt="">

You use this technique when you want a screen reader to ignore an image because it is used purely for "decorating" your page.