Mass loss refers to the process by which a system, such as a star or planet, gradually loses mass over time. This can occur through various mechanisms, such as stellar winds, nuclear fusion reactions, or evaporation due to intense heat. Mass loss can have significant effects on the evolution and dynamics of a system, leading to changes in its structure, composition, and overall behavior. Understanding mass loss is essential in studying the life cycles of celestial bodies and their impact on their surroundings.