**2. BitTorrent messages and parameters**

Analysis of BitTorrent client-centric behavior and, to some extent, swarm behavior, is based on BitTorrent protocol messages5. Messages are used for handshaking, closing the connection, requesting and receiving data.

The BitTorrent client will generate at startup a unique identifier of itself known as *peer id*. This is client dependent, each client encoding a peer id based on its own implementation.
