Regression testing is a crucial process that allows developers to catch bugs or errors introduced by recent changes in code, ensuring existing functionality remains intact. It's a way to verify that new features don't have unintended side effects on the product's overall performance. Regression testing can be automated or performed manually, and it's essential for detecting and fixing bugs before software hits the market, reducing costs and user churn. The process involves searching for bugs in previous updates and changes, as well as testing specific features to rectify existing bugs. It's typically performed semi-regularly or before major production releases, with teams choosing the frequency based on their budget and product complexity. There are different forms of regression testing, including unit regression, partial regression, complete regression, retesting, and others. Techniques such as test case prioritization, regression test selection, and retesting all test cases are used to streamline the process.