What is the purpose of the -Pn option in the Nmap command?

The -Pn option in the Nmap command is used to skip the host discovery phase. This means that Nmap will assume that the target is online and will directly start scanning the ports without checking if the target is reachable via ping (ICMP echo requests). This is particularly useful when firewalls block ICMP traffic, allowing you to scan targets that might otherwise appear offline.