Prime purpose of this lecture is to describe on the Transport Layer. Here major focus on to explain Services Provided to the Upper Layers, Transport Service Primitives and Berkeley Sockets. This lecture also briefly explain on elements of Transport Protocols, they are: Addressing, Connection Establishment, Connection Release, Flow Control and Buffering, Multiplexing and Crash Recovery. Finally discuss on Flow Control and Buffering, Multiplexing, Crash Recovery etc.