Laser Interferometry is a technique that uses the interference of laser light to measure small distances or changes in position with high precision. It works by splitting a laser beam into two paths, reflecting them back, and then combining them. The resulting pattern of light and dark fringes indicates any differences in the path lengths, which can be caused by movement or changes in the environment. This method is widely used in various fields, including metrology, gravitational wave detection, and optical engineering. One notable application is in the LIGO project, which detects gravitational waves by measuring tiny changes in distance caused by passing waves.