Nam is a Tcl/Tk based animation tool that is used to visualize the ns simulations and real world packet trace data. The first step to use nam is to produce a nam trace file. The nam trace file should contain topology information like nodes, links, queues, node connectivity etc as well as packet trace information. In this chapter we shall describe the nam trace format and simple ns commands/APIs that can be used to produce topology configurations and control animation in nam.