BitTorrent index
A BitTorrent Index is a list of .torrent files (usually including descriptions and other information). It should be differentiated from a BitTorrent Tracker, which merely coordinates communication between peers attempting to download the payload of the torrents. Many BitTorrent websites act as both tracker and index. Sites such as these publicize the tracker's URL and allow users to upload torrents to the index with the tracker's URL embedded in them, providing all the features necessary to initiate a download.