Regression testing is done to ensure that any new change in the software will have no negative effect on working of other parts of the software. It is to make sure that any modifications will not bring other bugs to appear. It is a part of program development process.

In this testing, we follow rerunning of previously run tests just to check if the functionality of our software is showing any unwanted changes.

To determine whether the changed component has introduced any error in unchanged component or not....

Regression Test: Retest the application affter changes in application or atmosphere.

After the Bug get fixed, testing the application whether the fixed bug should not affecti remaining functionality of the application . Majorly in regression testing Bug fixed module and it's connected modules are checked for their integrity after bug fixation.

regression testing is nothing but testing the already tested functionlity again and again