A .torrent file is a metadata file used by the BitTorrent protocol. It doesn't contain the actual data being shared, but rather information about the files and folders to be distributed, including their names, sizes, and checksums. Crucially, it also contains the URL of a tracker, which is a server that helps coordinate the transfer of data between peers (users) in the BitTorrent network. When you open a .torrent file with a BitTorrent client, the client reads this metadata and uses it to connect to the tracker. The tracker then provides the client with a list of other peers who have parts of the file you want to download. The client then downloads the file in small pieces from multiple peers simultaneously, reassembling them into the complete file. This decentralized approach allows for efficient and robust file sharing, especially for large files. Torrent files are small in size, typically ranging from a few kilobytes to a few megabytes, as they only contain metadata and not the actual content.