A firewall between you and the outside world makes your computer a bit safer. Usually however, firewalls check and block incoming traffic and leave you in the dark about traffic going out. When does your Mac “contact” the outside world to send information, or to get a reply back? Little Snitch tells you; it did from day one its developer released it. Shortly, Little Snitch will be at version 3, and it will do it better, more complete (incoming as well) and user-friendlier than ever before.