Seeders - users with complete copies of files described by the torrent. Leechers - users with incomplete, mid-download files. Seeders send pieces to leechers who send pieces to other leechers.
A 'seeder' of a torrent file is one providing the file so it is available for sharing. A 'leecher' is one who is receiving the file but not sharing it.
The seeders are the people (computers) where the torrent files are completed and they share them with the rest. The leechers are those that download the files.
Torrent seeders are the people who would have uploaded the file and sharing the same for you to download, Torrent leechers are the people who are downloading the file.
