Vuze (formerly Azureus) is a Java based BitTorrent client. It offers multiple torrent downloads, queuing/priority systems (on torrents and files), start/stop seeding options and instant access to numerous pieces of information about your torrents.
It also features an embedded tracker that is easily set up and ready to use. Vuze connects to the BitTorrent network.
BitTorrent is a peer-to-peer protocol designed to transfer files. Users connect directly to send and receive portions of a file. Central tracker coordinates the action of all peers and manages connections without knowledge of the contents of the files being distributed. With BitTorrent, users upload at the same time they download, so network bandwidth is managed as efficiently as possible.
BitTorrent is designed to work better than other file transfer protocols as the number of people interested in a certain file increases.