It's a Bittorrent tracker. Are you running a Bittorrent client to download files?

A tracker in a Bittorrent swarm organizes the seeders and leechers. You don't need a tracker though, you can just use DHT when creating a torrent. You can also use Openbittorrent's tracker.

A BitTorrent tracker is a server that assists in the communication between peers using the BitTorrent protocol. It is also, in the absence of extensions to the original protocol, the only major critical point, as clients are required to communicate with the tracker to initiate downloads. Clients that have already begun downloading also communicate with the tracker periodically to negotiate with newer peers and provide statistics; however, after the initial reception of peer data, peer communication can continue without a tracker.
- Wikipedia (http://en.wikipedia.org/wiki/BitTorrent_tracker)

A torrent tracker such as thepiratebay, requiring a torrent client such as bittorrent.

The Index of Private Tracker Abbreviations is an index that lists the abbreviated names or acronyms of BitTorrent private trackers. For example AOM is the acronym for Art of Misdirection.