Every time a developer makes a change to a code, there is some impact on a system. Ideally, the impact is either fairly small or fully expected. The goal is to implement the change to make its influence on the system in the right way and select the best option available. That is when a software impact analysis is relevant.
Impact analysis is the process of analyzing, predicting, and estimating the potential consequences before carrying out a change in the deployed product, focusing on unexpected side effects of a decision or change in a system and indicating potentially affected areas. It tells us what part of the system can be unintentionally affected by a change and helps deal with potential problems before they arise.