Seeding and Reseeding

What is a seed?
A "seed" is a computer that has a complete file available for other computers to download via the Bit Torrent Protocol. The term "seeding" is used to describe the process of providing other computers access to that file via the Bit Torrent Protocol. In order to "seed", one of two things must occur:

1. The computer with the complete file must leave the download client open after the download completes. This allows other computers to access the file (they are only able to access the download file while the download client is open). Once the "seed" computer closes the download client, the "seeding" ceases.
2. A computer can become a "seed" by attempting to download (specifically overwrite) a file that has already been successfully downloaded. The Bit Torrent client will identify that the file has already been downloaded and initiate the computer as a "seed".

What is reseeding?
Reseeding means seeding a file again, after its initial release. If a given download file does not have any seeds, and the combined data of the peers does not produce a complete version of the file, then all the peers eventually will get stuck with an incomplete file. When this happens, a peer with the missing data required for a complete file must connect to allow the other peers to download the missing pieces. When this occurs, it is called reseeding.

Why should I leave the client open after it finishes downloading?
In the community of torrent downloaders, it is considered polite to leave your download client open as long as possible - as this allows others to share your download files.

What is a swarm?
A swarm is a group of peers and seeds that are connected for a particular file.

What is leeching?
Leeching describes a person who downloads but does not seed any files, but is not as common on a BitTorrent network than it is on other file sharing networks.