In this chapter, we are going to learn Network Address Translation (NAT) as configured on Cisco routers in common network scenarios. First time NAT users find NAT concepts difficult to grasp and NAT configuration difficult to create and understand. But the fact of the matter is that the basic concpets of NAT are pretty simple as we will see below. After developing an intimate understanding of basic NAT concepts early in the chapter, we will learn how to configure and troubleshoot NAT using the Cisco command line interface (CLI). Toward the end of the chapter, we will also see how NAT can be configured the easy way using Cisco Configuration Professional (Cisco CP).