Planet migration is a phenomenon in which planets in a planetary system change their orbits over time. This can be caused by various factors, such as gravitational interactions with other planets, interactions with the protoplanetary disk from which they formed, or interactions with a passing star. Planet migration plays a crucial role in shaping the architecture of planetary systems and can have significant implications for the habitability of planets within those systems. Understanding planet migration is important for studying the formation and evolution of planetary systems, as well as for predicting the future dynamics of planetary orbits.