What is a firewall?

One of the most basic ways to safeguard a computer online is to eliminate the ability of other computers to connect to it. This can be done entirely or selectively. The software providing this functionality is referred to as a firewall. In it’s simplest form firewalls simply block incoming connections to various ports on the protected machine. But they can be much more complex and use a great deal of state and history to determine whether to allow certain connections.

Credits: Talking: Geoffrey Challen (Assistant Professor, Computer Science and Engineering, University at Buffalo). Producing: Greg Bunyea (Undergraduate, Computer Science and Engineering, University at Buffalo).