ask: in the ADD form gives it a field: Attach a file.
For what does this field serve? What is high-loaded here?

urs

Starting with the last beta, you can upload a file to be attached to a Link.

The most obvious use would be for logo/graphics advertising.

But, the uses are not limited to anything. What you do with the file is up to you. Links will upload it... but that's about all. Beyond that, you need to determine the purpose of that upload.