A. Request Tracker (RT) is an automated system to monitor, answer, and document requests. RT comes with Web, command line, and email interfaces to its Mysql-backed data store. The user submits a form asking for help. RT send the user an electronic "ticket stub" which is used in future correspondence to refer to this problem. It also sends the user's request to the queue members, one of whom writes a reply, which RT records and forwards to the user. The ticket is then resolved.
User guide - Web interface | Developer guide
Q. What is a ticket?
A. A ticket is an item created by the public, or another imcista. It can be a bug, usage report, suggestion or whatever.