Firewall
A method of protecting one network from another network. A firewall blocks unwanted access to the protected network while giving the protected network access to networks outside of the firewall.
A company will typically install a firewall to give users access to the Internet while protecting their internal information.
Firewall are either software-only or separate software and hardware combination that serves to protect an internal network or a computer from attacks and unauthorized access by sitting between the Internet and the internal network.