Overnet is a P2P file sharing application like so many others.

For those of you that have heard of eDonkey 2000 or Emule, you may be aware that overnet uses the same transfer protocol so files can be shared between them.

This may lead many to believe that the networks are therefore identical, but there are a couple of differences:

ED2K utilises servers, and users tied to a server can not search the entire network (meaning your amount of download sources is limited)

Overnet on the other hand claims to be completely decentralized, meaning when you search and download, you have access to every user on the entire network. Overnet can be considered as a better version of ED2K, and indeed, there doesn't appear to be anything ED2K does that Overnet doesn't.

Overnet and Kazaa: Overnet seems to perform much like eDonkey in the way that it is more useful for rarer or larger files, where kazaa is better for smaller and more common files. See more here.

Overnet and BitTorrent: Overnet has some similarities to BitTorrent, mainly that you can't stop people uploading off you without effecting your download speeds, and also that people can download an incomplete file off you. For those of us with transfer limits, this is certainly a problem.