What does the <base> tag specify in an HTML document?

The tag in an HTML document is utilized to define the base URL for all relative links within the document. When the tag is specified, it sets a reference point for both hyperlinks and resources that use relative paths. This means that if you have links that are not complete URLs (i.e., they do not start with "http" or "https"), the browser will prepend the value of the URL to those relative links, allowing the browser to correctly resolve them.

For instance, if you have a tag, and then a relative link like would resolve to "http://www.example.com/folder/page.html". This functionality simplifies the management of links in a document, especially when dealing with nested directories or when moving files to different locations.

Understanding the purpose of the tag is crucial for maintaining the integrity of your links and ensuring that users can navigate your website correctly and efficiently.