Put simply, decorative images are pictures or graphics that are:
This is in accordance with the Web Content Accessibility Guidelines (WCAG) 2.0 and with the HTML5 standard.
When adding an image to your page, news story, event, or profile, you’re required to provide either a caption or description (ALT text).
This is because often such images are informative (graphs, charts, maps, product images, infographics, screenshots). Sometimes they’re functional (images acting as links). In both these cases, the images clearly need a text alternative that will be presented to visitors using screen-readers or other assistive technology.
In LiveWhale 2.6.0 and before, caption was required and used for ALT text. A separate “Description (ALT text)” field was added in LiveWhale 2.7.0 for cases where your screen-reader description and marketing caption might be different.
In LiveWhale, indicating that an image is decorative exempts you from needing to supply a caption or ALT text. Basically, it’s used for any images that a screen-reader should ignore.