This document provides an introduction to network concepts for a training module on setting up computer networks. It defines key terms like client, server, media, network adapter, and protocols. It also explains different types of computer networks including local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), storage area networks (SANs), and virtual private networks (VPNs). The goal is to give trainees background knowledge needed to understand network installation and configuration activities covered later in the module.