It It is important to consider users who may have visual impairments when developing content that contains images and other visual elements. Screen readers and computers are not capable of interpreting visual information in a text or audio version on their own. Alternative text describes visual information in a text-based format. Screen readers read the text-alternative in place of images. WebAIM is a good starting resource for alt tag principles.
Follow these best practices when including images in your content that provide meaning:
- All Images need to have an Image Description (Alternate text or ALT tags) included. You can check this by editing the content item that contains the image, select the image, and click the Insert/Edit Image tool.
- Alt tags should be very brief and descriptive but not redundant. Don't repeat the same content from the image into the alt text.
- Avoid using "Image of..." since this is understood to be an image.
- Sometimes decorative images are used for formatting or layout of content (borders, horizontal separators, spacer images). You do not need to include alt text for these images because they do not hold meaning.
- Advanced or complex images (maps, logos, background images, etc.) cannot be fully described in alt text. WebAIM provides some suggestions for how to approach several types advanced images.
