A maser is a device that amplifies microwave radiation through a process called stimulated emission. It works similarly to a laser but operates at microwave frequencies instead of visible light. Masers are used in various applications, including telecommunications, satellite communication, and scientific research. The term "maser" stands for "Microwave Amplification by Stimulated Emission of Radiation." They were first developed in the 1950s and have since contributed to advancements in fields like quantum physics and astronomy. Some masers are even used in deep-space missions to improve communication with spacecraft.