Alternative Text

An image used in web content needs a meaningful alternative text description. Called an "alt tag" or "alt text," it is used by screen-reading tools to describe an image to visually impaired readers. An image used only for decoration should have an empty alt tag (alt="") to tell screen readers to ignore it. (See Best Practices below for information on how to mark images as decorative on Digital Commons.)

Alt text also has important benefits for your website rankings. Search engines crawl alt text, so optimizing your images' alt text is an easy way to improve the user experience for all visitors, regardless of how they find your page.

Descriptive vs. Specificity

Bodie Island Lighthouse seen on North Carolina Outer Banks

Bad Alt Text


This line of alt text technically follows the "be descriptive" rule, but it's too general. The image does show a lighthouse—more specifically, Bodie Island Lighthouse on North Carolina's Outer Banks. It's important to include specifics like that in alt text. Search engines need them to properly crawl the image, for example, if it's on a web page about North Carolina lighthouses.

Good Alt Text

Better alt text for this image might be:

alt="Bodie Island Lighthouse on North Carolina Outer Banks"

Depending upon the subject of your content, you might also mention the scenic landscape.

Best Practices

  • Describe the image in its context, and focus on the details the image adds to the text.
  • Be specific, but try make the alt text fewer than 125 characters. 
  • Do not use the phrases like "image of" or "picture of" in the description. They are repetitive because screen-reading tools identify images from the HTML source code.
  • Use an empty alt tag (alt="") for decorative images. Note: When uploading a decorative image on Digital Commons, you only need to click on the "Decorative Image" checkbox. You don't need to add the quote marks ("").