In this paper, the authors present an overview of current transport layer protocols. They focus on the two well-known transport layer protocols for Transmission Control Protocol/Internet Protocol (TCP/IP) model called Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). They mainly discuss the TCP/IP services, features and structures. TCP is used as the reference point for comparison. This paper also presents a survey on a new transport layer protocol called Stream Control Transmission Protocol (SCTP). At the end of this paper, they summarize and make a comparison between UDP, TCP and SCTP.