RT, or Request Tracker, is an enterprise-grade ticketing system which enables a group of people to intelligently and efficiently manage tasks, issues, and requests submitted by a community of users. That's what the website says anyway.

In plain English, it's a system that lets you manage trouble tickets or service requests, which can be submitted via email or by using a web based interface. Almost all of the interaction with the system after a ticket has been created is performed via a web interface.

The system is written in Perl and the majority of installations use MySQL as the database back-end. It has a very good reputation and is used world-wide in a number of different industries.