Seeders and leechers are two types of users in the BitTorrent file-sharing network. The main difference between them is that seeders have already downloaded the complete file and are sharing it with other users, while leechers are currently downloading the file but have not yet completed the download. Seeders are important to the networks functioning since they give the initial copy of the file from which other users can download, while leechers rely on seeds to download the file. Seeders increase download speed, while leechers lower it. Once a user has downloaded enough of the file to become a seeder, they will start sharing the file with others. A leech who downloads files shared by seeders but does not seed back to other users is called a "leecher".