What is image alt text?
Alt text is a short description of an image that will help people with visual impairment. This label is not visible in your typeform, but screen readers will read it out loud.
You can use the Alt text field in question settings to manually describe the picture you’re adding in maximum 125 characters.

Tips! If you’re adding an image from the Unsplash library or an icon from the Noun Project the description of the image will appear automatically in the Alt text field. We do recommend reading the description that comes automatically, and making adjustments, if needed.
This is a question with an Image layout and Alt text in its question settings:
If you don't want to use image alt text for a picture that only serves decorative purposes, you can simply select the Decorative Image checkbox to disable image alt text.
If you want to restore previously entered image alt text, you can do that in one click by deselecting the Decorative Image checkbox.
Here’s a Picture Choice question with automatically populated alt text in the Question alt text section of its Question settings:
The Decorative Image option is not available for the images of the Picture Choice question type.