ZoneAlarm is easy-to-use firewall that blocks hackers and other unknown threats. ZoneAlarm is free for individual and not-for-profit charitable entity use. This program includes four interlocking security services: a firewall, an application control, an Internet lock, and Zones. The firewall controls the traffic from and to your computer, with application control you can define which applications can connect to Internet, with Internet lock you can define which software can connect to Internet while your computer is unattended and Zone monitors all activity on your computer and alert''s when new application tries to access the Internet.