Appropriate Alternative Text (Alt attribute) must be provided for all non-decorative or linked images so screen reader users can understand the message conveyed by the images on the page, or the link added to an image. Proper use of alt text is required for ADA Compliance.
Alternative Text Example
The Alternative Text should contain the message being conveyed by the image. If the image includes text, the text should be included in the alt text. Complex graphics (infographics) should be accompanied by detailed text descriptions. Images used for decorative purposes can be marked decorative in lieu of alt-text.
Purely decorative images or images already described by the surrounding content can be marked as decorative so the screen reader user isn’t distracted from the more important content of the page. The Foxbright CMS provides a checkbox to mark an image as decorative if Alt text isn't required.
Images Used as Links must have Alternative Text
If an image is used as a link, make sure the Alternative Text describes the link destination.
Extensive Guides to Alternative Text
SSA Alternative Text Guide https://www.ssa.gov/accessibility/files/SSA_Alternative_Text_Guide.pdf
WebAIM Alternative Text Basics http://webaim.org/techniques/alttext/