A torrent file is a small file that contains metadata about files and folders to be shared over the internet using the BitTorrent protocol. It does not contain the actual content but instead provides information such as file names, sizes, and the locations of other users (peers) who have the content. This allows users to download and upload files in a decentralized manner. When a user opens a torrent file with a BitTorrent client, the client connects to other peers to download pieces of the desired files. This method of file sharing is efficient because it allows multiple users to share the load, making downloads faster and reducing the strain on any single server.