Filename

A filename is the name a file is given. In most Operating Systems, this name is unique and identifies the file it is refering to (usually the unique identification is a combination of path + filename).

In the ed2k and Kademlia protocols, the identification doesn't need a filename, but filenames are supported since they provide a human-friendly way of identifying them.

Also, they will be used to create the file, when it is completed, since, as mentioned before, the Operating System will most likely require a filename.