Nmap is short for Network Mapper. It is an open-source security tool for network exploration, security scanning, and auditing. However, the Nmap command comes with lots of options that can make the utility more robust and difficult to follow for new users. The purpose of this guide is to introduce a user to the Nmap command line tool to scan a host or network to find out the possible vulnerable points in the hosts. You will also learn how to use Nmap for offensive and defensive purposes. Let us see some common and practial nmap examples running on Linux or Unix-like systems.