Writing Appropriate ALT Tags for Images

The ALT tag is a feature of the HTML code that is associated with an image on a webpage or within some electronic documents. The ALT tag defines the alternative text that will be displayed if the image is not available. This is also the text that will be read aloud to someone using a screen-reader device. 

For that reason it is very important that the text of the ALT tag be descriptive of the image. It is not enough to merely add ALT text such as “Image 1” or “flower.” Be more specific and convey any meaning that may be missed by someone who cannot see the image, such as ALT=”man petting large alligator.” There is no need to include the phrase “image of,” since a screen reader will state that before reading the ALT tag text.

Our Moodle LMS will prompt you to add an ALT tag text as you upload and display images in your course. When the image property box appears on your screen, either when you are uploading or editing an image, type the appropriate text in the description box and then save the changes.

If your image contains written text, this text will not be accessible for someone using a screen-reader or otherwise unable to see the image. If the text phrase is a small phrase, consider putting into the ALT tag. If the words are more than a short phrase, instead put the text in an HTML element such as a label or Moodle Page. Table data should never be placed as an image, but rather as an HTML table with tagged column and row headings.