A visible URL in the image. A URL is a line of text that, when typed out into an address bar, directs you to its web page.
examples of URLs are as follows:
www.furaffinity.net/user/exampleURL (this is an artist page, it can be a string of numbers instead)
e621.net/post/show/exampleURL (this is an image page, it can be a string of numbers instead)
If you can type it in and it directs you to a page, then it's a URL. The ones without https or www need to be typed into the address bar to direct you to their page.
Examples that are not URLs:
These are not URLs because when put into the address bar, they will not direct you to their page. They, instead, send you into your search engine to find the above, or send you into an invalid (page/server not found) "page".
The following tags are aliased to this tag: web_address