A peer is a person who is downloading a file from a seeder, but who does not have the complete file yet. A seeder is someone who has the full file and is sharing it with others. Torrents are a way of distributing large files over the internet using a peer-to-peer network. In a torrent, the file is divided into small pieces and each peer can download and upload pieces from other peers. This way, the download speed is increased and the bandwidth is distributed among the peers.