This book describes every basic concept of networking. We have covered different parts of computer network architecture and figured out the difference between TCP/IP and OSI model.Firstly we have started from computer networking devices like NIC, hub , switch, router, bridge , router and gateway. we have covered each and everything about networking devices and about cable and wire viz OFC and twisted pair cables.We have covered different addressing system in computer network like logical , physical and service point addressing system and understand their real time application with representation.We have covered different data link protocol like Ethernet, token ring with their frame format-also covered error correction and detection techniques in detail.In Next unit we have covered Network layer with features of layer 3 architecture with explaining logical addressing system in detail along with classes of IP address and their application in subnetting and supper netting and difference between IPV4 and IPV6, afterword we have explained transport layer and their functionality in detail with difference between TCP and UDP.