An alt tag is a text alternative for an image or object on your page. The alt tag will be read by screenreaders and other site readers as an alternative to the image itself.
They are important because they make sure that the content of your site is easy to understand and available to everyone who wants to view or read it.
To set up an alt tag for an image on your site, select the image by clicking on it. Then in the SiteMaker Editor, click on the 'Style' tab, and then the 'Alt tag' button. Ensure that the 'Display alt text' option has been selected. You can now enter a full description of your image so that it will be read as a text alternative. Try to give a full description of the image and imagine how you would describe it to someone who couldn't see it.