Bugzilla is one example of a class of programs called "Defect Tracking Systems", or, more commonly, "Bug-Tracking Systems". Defect Tracking Systems allow individual or groups of developers to keep track of outstanding bugs in their product effectively. Bugzilla was originally written by Terry Weissman in a programming language called "TCL", to replace a crappy bug-tracking database used internally for Netscape Communications. Terry later ported Bugzilla to Perl from TCL, and in Perl it remains to this day. Most commercial defect-tracking software vendors at the time charged enormous licensing fees, and Bugzilla quickly became a favorite of the open-source crowd (with its genesis in the open-source browser project, Mozilla). It is now the de-facto standard defect-tracking system against which all others are measured.
The BugPort system is an open-source, freely available, web-based system to manage tasks and defects throughout the software development process. BugPort is written with the PHP language using its object-oriented capabilities and is in use by INCOGEN for internal management of software development and QA.