Leech (computing)

In computing and specifically Internet, a leech is one who benefits, usually deliberately, from others' information or effort but does not offer anything in return, or makes only token offerings in an attempt to avoid being called a leech. In economics, this type of behavior is called "free riding" and is associated with the free rider problem.

Depending on context, leeching does not necessarily refer to illegal use of computer resources, but often instead to greedy use according to etiquette: to wit, using too much of what is freely given without contributing a reasonable amount back to the community that provides it.

The name derives from the leech, an animal that sucks blood and then tries to leave unnoticed. Other terms are used, such as "freeloader" and "sponge", but leech is the most common.

In games (whether a traditional tabletop RPG, LARPing, or even MMORPG) the term "leech" is given to someone who avoids confrontation and sits out while another player fights and gains experience for the person, or "leecher", who is avoiding confrontation.

Amongst users of the file distribution and common P2P networks, such as the eDonkey network or Gnutella2, a leech is a user who disconnects as soon as he/she has a complete copy of a particular file, while minimizing or completely suppressing data upload.

However, on most BitTorrent tracker sites, the term leecher is used for all users who are not seeders (which means they do not have the complete file yet). As BitTorrent clients usually begin to upload files almost as soon as they have started to download them, such users are usually not freeloaders (people who don't upload data at all to the swarm). Therefore, this kind of leeching is considered to be a legitimate practice. Reaching an upload/download ratio of 1:1 (meaning that the user has uploaded as much as he has downloaded) in a BitTorrent client is considered a minimum in the etiquette of that network. In the terminology of these BitTorrent sites, a leech becomes a seeder (a provider of the file) when he finished downloading and continues to run the client. He will remain a seeder until the file is removed or destroyed (settings enable the torrent to stop seeding at a certain share ratio, or after X hours have passed seeding).

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