What is alt text?
Alt text is the short text description paired with every image on a webpage or in an app. Screen readers speak it aloud for people who cannot see the image, search engines index it as context and browsers show it when the image fails to load. The goal of alt text is to carry the same meaning the image carries, in plain language and as few words as possible. Purely decorative images take empty alt text so screen readers skip them entirely.
Informative image: Line chart showing weekly active users rising from 2K to 5K between January and June.
Functional image, link or button: Open the settings menu.
Decorative image: empty alt text ("").
Why does alt text matter?
Alt text is the part of your content that most readers never see, and the one that matters most for accessibility. A missing or lazy alt attribute ("image1.png") leaves screen reader users with a hole in the page. Beyond accessibility, alt text shapes how search engines read images and how social platforms render link previews, which makes it a small surface with outsized reach. A brand voice that ignores alt text is signaling that accessibility comes last.
How do you use alt text?
Describe the information the image conveys, not the image itself, and skip phrases such as "image of" or "picture showing," since screen readers already announce that the element is an image.
Keep alt text under about 125 characters, which is the limit most screen readers read in one pass.
Use empty alt text for purely decorative images so screen readers do not announce them at all.
