An interferometer is a scientific instrument used to measure the interference of waves, typically light or radio waves. It works by splitting a wave into two paths, then recombining them to observe patterns of constructive and destructive interference. This allows scientists to make precise measurements of distances, wavelengths, and other properties of waves. Interferometers have various applications in fields such as astronomy, metrology, and optics. For example, the Michelson interferometer is commonly used in experiments to measure the speed of light and in the detection of gravitational waves. These devices are essential for advancing our understanding of physics and the universe.