If you plan to study everything that is generalized, it is customary to call information security, then sooner or later (and rather sooner) you will hear or learn about such a utility as Nmap. Someone may say: “Ah, what’s there? Just scan the ports. ” Do not listen to these people. Knowing the capabilities of Nmap commands and the ability to use it, in itself already gives serious opportunities in the practice of pentest. And in this article I will try to show you the basics and give the most necessary recipes for using Nmap, as well as explain how it works.

if you are really into pentesting you should learn How to use nmap

When a software get ported to all those OS it’s a mark for how important that software is,
Whatever you are trying to do as a network Administrator or a Penetration Tester you will need to work with Nmap one day