Images and graphics can be helpful for your webpage, as they make content easier to understand and they help people orient themselves to the content on your webpage. It is important to add alt tags to your images and graphics —without them it can be frustrating for people to navigate through your site. 

In order to be WCAG AA compliant, all images must have accompanying text that conveys the same information. Images that add no meaningful information should be marked as decorative. Doing so will prompt assistive technology to ignore these elements and they will not be flagged for accessibility issues.

Word

1. Right click or Ctrl click on the image.
2. Select Format Picture.
3. Select Layout and Properties.
4. Expand Alt Text.
5. Enter the Title and Description. For decorative images, enter empty quotation marks (””) in the Description field.

InDesign

1. Use the Selection Tool to select the image.
2. Under Object, select Export Options.
3. Select the Alt Text tab.
4. Enter the alt text. For decorative images, enter empty quotation marks (””).

Read Adobe's documentation about how to add alt-text to images in InDesign.

Adobe Acrobat

1. Use the TouchUp Reading Order tool to select the image.
2. Select Figure for images that show content (double-click the image if Figure is not selectable) OR, for decorative images, select Background and skip the remaining steps.
3. Right click or Ctrl click on the image.
4. Select Edit Alternate Text.
5. Enter the Alternate Text.
6. Select OK.

LinkedIn Learning has a tutorial on adding Alternate Text in Acrobat DC.

Recommendations

WebAIM provides guidelines for creating appropriate alternate text which include:

• Be accurate and equivalent
• Be succinct
• Avoid redundancy
• Avoid “image of…” “graphic of….” “photo of…” “link to…”

For more information, see the Social Security Administration Guide: Alternate Text for Images.
Some best practices to use when writing alt text can also be found at Accessibility: Image Alt text best practices