Disk evolution is a research area within astronomy and planetary science that focuses on understanding how protoplanetary disks, or circumstellar disks, evolve over time. These disks are structures of gas and dust that surround young stars and are the birthplaces of planets. Researchers study disk evolution to better understand the processes that lead to the formation of planets and planetary systems. This includes investigating how disks lose mass and angular momentum, how they interact with the central star, and how they dissipate over time. By studying disk evolution, scientists can gain insights into the conditions that lead to the formation of different types of planets, as well as the overall evolution of planetary systems.