It is a term that is used for a little piece of data that is sent over a network. Might be a LAN, WAN or MAN. 'Packet' data includes several bits of data that controls information and has the right parts in order to arrange it properly and convert it in to its original form at the platform it is received. Packet data does not have a specified size. It varies from network to network. Moreover, packet data might also be referred to as a block, frame or cell.