This books includes 16 chapters which cover Fundamental concept of Computer Networks. Chapter 1 includes the concept, type and utility of computer network. Chapter 2 network types, characteristics and formation of Local Area Network has been discussed. Chapter 3 Basic and hybrid types of computer Network topology and types of other topologies are included. Chapter 4 includes communication and transmission of data, forms of signal and hardware communication. Chapter 5 forms of transmission technology, hardware communications, switching and frame have been discussed. Types of cables and connectors are discussed in chapter 6. Chapter 7 various wireless networks are given. Chapter 8 includes Computer network Interface card, database, its structure and usability. Chapter 9 Network Reference model includes discussion on OSI and TCP/IP model. Chapter 10 Ethernet has been discussed. Network protocol, rules, data access and data packet information has been given in Chapter 11. Chapter -12 includes discussion on inter- network device. Chapter -13 types in the Internet system, its utility and remote access server are discussed. Chapter 14 Network System includes the scale, security and performance of network system. Network Service, type, form, and features such as utilities, safety and performance have been discussed in chapter -15. Discussion about network tool is been given in chapter 16.