I didn't know you could do that!
Topic: Quick send documents via Skype 4 Business
You're chatting with someone on Skype 4 Business and you want to have them send you a file. So you're thinking "ok, send as an attachment in email", or "share it OneDrive" but nooooo. It's much easier than that - just drag and drop the document into the chat box. Done!
Documents sent this way are inspected for malware by Microsoft. Certain extensions are not allowed (executables for the most part).
You download will be on the C: drive in the "My Received Files" folder, but can be modified via Tools->Options->File Sharing.
In addition, the file transfer is encrypted making it a safe choice as well.
Ports 50,400 through 50,059 from the source are used for this kind of transfer which is exactly the same port range used for Application Sharing.