Regression Planning is a Release Planning feature that allows you to define and map out coordinated sets of testing activities to ensure your existing functionality continues to work as designed. This is particularly critical for development projects in which new features are added.
A regression plan can contain multiple Regression Suites. Regression suites represent a set of related regression tests within a regression plan that, together, ensure proper functioning within a given aspect of the application. Teams can build and manage an inventory of regression tests, create test plans for each new release, and manage the testing activities within the course of the team's sprint/iteration schedule.
Regression Testing is an optional set of functionality that can be disabled or enabled through the Administration component.