This session starts with introduction to Client Server paradigm. Then a detailed comparison of TCP and UDP sockets is discussed with examples. Three way connection establishment and four way connection termination is compared and shown practically using Wireshark tool. The system call graph of Internet domain TCP Client and server is described. The related system calls for creating and managing the sockets are discussed. Proof of these concepts is given by example codes of echo and daytime clients and servers. Some important lookup functions like gethostbyname() and getservbyname() are discussed with examples. Finally, the session closes with a description of assignment on writing your own web server.