A look at another enormously popular file sharing tool, eMule. Along with BitTorrent, there is another P2P network that the movie and music makers would dearly love to shut down: eMule. Originally popular with movie traders because of its exceptional ability to handle large files, eMule is now massively popular with file traders of all stripes, and more and more legitimate, legal downloads are appearing on the network.

eMule began life as an open-source clone of file-sharing program eDonkey2000 (hence the network is often referred to as the eDonkey network), and quickly became more popular than the original program. Being open source, a number of modified versions of eMule have sprung into existence.

eMule is, in many ways, easier to use than BitTorrent. It is entirely self-contained; that is, you don't have to go out onto the Web looking for torrent files or the like. It works very much like Kazaa or Napster - you install the program, do a search, and double click on any files matching your search query that you'd like to download. In terms of the number and variety of files available on the network, no other peer to peer program can match it.

On the downside, it tends to be considerably slower than BitTorrent, especially if you're trying to get hold of rare files. With BitTorrent, you get pretty much instant gratification -- the download kicks off immediately. With eMule, you may have to wait several days before your download even starts.

As with BitTorrent, files are broken into chunks, and you can be downloading multiple chunks of a single file from different users (in fact, you may be downloading a single file from dozens of users simultaneously). By the same token, you can be sharing chunks of an incomplete file - in effect, sharing the parts you have while downloading the parts you don't.

As with any other peer to peer program, you will need to open a port in your software firewall (if you use one) or set up port forwarding on your router. The default port for eMule is 4662, although this can be changed in the software settings. As with BitTorrent, it is possible to use eMule without an open port (you get what is called a LowID when it tries to connect to the network), but it will be incredibly slow since other eMule PCs will not be able to communicate directly with your PC.