There are two types of firewalls: hardware firewall and software firewall. The router functions as a hardware firewall, while Windows includes a software firewall. You can also install other third-party firewalls.
In August 2003, by connecting the Windows XP system to the Internet without a firewall, the Blaster worm could be caught in minutes, making the network's most vulnerable services on the Internet.
In addition to reinforcing the importance of installing security patches, it also strengthens the importance of using a firewall, which prevents traffic from entering the network.