Regression testing is a vital software testing process that aims to ensure that new code changes do not adversely affect existing functionality. It involves retesting the parts of an application that might be impacted by code modifications bug fixes or new features. This type of testing helps verify that the new code does not introduce new bugs or unintended changes to the already tested and functioning parts of the software. By running regression tests developers can catch any potential issues early on before they escalate and impact the overall quality of the software. For example let's say you have an e-commerce website and you decide to update the checkout process to improve user experience. By conducting regression testing you would verify that this checkout update did not unintentionally break other parts of the website such as product search or user account functionality. In practical terms regression testing can be carried out manually or using automated tools. Automated regression testing is efficient for repetitive tests that need to be run frequently whenever there is a code change. Test scripts can be created to automatically execute these tests saving time and effort while ensuring comprehensive test coverage. In conclusion regression testing is essential for maintaining the reliability and integrity of software systems by confirming that new changes do not introduce defects into previously working code.