This subject examines the OSI and TCP/IP transport layer, which is essential for end-to-end networked system communication. Students will learn how transport layer protocols move data, start sessions, and assure delivery integrity. Most attention is paid to TCP and UDP, the main transport protocols. Sequencing, acknowledgments, flow control, and error recovery are aspects of TCP, like registered mail that requires confirmation. UDP is portrayed as connectionless, quicker, and less dependable, appropriate for time-sensitive transfers like VoIP or video streaming. The module handles transport layer session creation, maintenance, and termination and service identification using port numbers. Students will also study how three-way handshakes, retransmissions, and congestion control procedures improve reliability. This subject will teach students the transport layer's basic properties, session establishment methods, and dependability mechanisms, enabling them to analyze and debug real-world networking issues.