This document provides an introduction to computer networks. It discusses that a network allows computing devices to share resources and information. Networks become powerful when multiple computers can communicate and share resources across different networks. The document then covers the need for networks by describing standalone computers and "sneakernet" data transfer. It also discusses how networks enhance communication through email and sharing information efficiently. Networks allow sharing of data, applications, and peripheral devices located in a central location. They facilitate centralized management and maintenance of operations. The document classifies networks based on geography into LANs, MANs, and WANs. It also categorizes networks based on roles into peer-to-peer, server-based, and client-based.