Alt text, also know as alt tags or description tags, is written text that is coded into the image on a website. There are three main reasons to add alt text to your images:
Website Accessibility - Adding alt text can help increase your website accessibility. Visually-impaired users can use screen-reading tools describe your image to them.
User Experience - When an image file cannot be loaded, the alt text will show in place of an image so the viewer doesn't have to guess what might have been in the empty image space.
Search Engine Optimization (SEO) - Alt texts can also help search engines better crawl and rank your websites
How to Add Alt Text To Your Website Images
The way you add alt text to your website images will differ based on what type website section you're editing: Images/Boxes or Rich Text Editor section.
If you're using an image or boxes section, the alt text is automatically added to your image based on the headline used with your image. If you've chosen to hide your headline(s), the alt text will still automatically get inserted into your image. If you need to modify the alt text in a section with the headlines hidden, unhide the headline, edit the headline to the alt text you want to use, and then hide it again.
Rich Text Editor Section
If you're using a rich text editor to add your images into your website, you will want to add an image first. Use the "Add Image" icon to insert your image into the section.
Once you've added your image, click on the image to select it. The image should turn blue and/or white boxes will appear on each corner. This indicates the image is selected. Click on the "Insert/Edit Image" icon to modify the image.
A "Insert/Edit Image" window will pop up with options. Under the general tab, add your alt text to the "Image Description" field.
Alt Text Best Practices
Keep It Short - You want your alt text to be descriptive, but also brief. Ideally aim for your alt text to be less than 125 characters since most screen-reading tools only read that amount of characters.
Jump Right Into The Description - Avoid using words like "Image of" or "Picture of". Go right into the image's description. Screen-reading tools will identify to the reader it's an image already, so it will be redundant to say it's an image.
Sparingly Use Keywords - Only include your article's target keyword if it's easily included in your alt text. Try to stick to using one keyword to avoid keyword stuffing which search engines typically frown upon.