Gravitational lenses, also known as gravitational lensing, is a phenomenon in which a massive object, such as a galaxy or a black hole, bends and distorts light from a background object, such as a star or a galaxy, that is located behind it. This distortion creates multiple images of the background object or can amplify its brightness, allowing astronomers to study distant and otherwise faint objects that would be difficult to observe using traditional telescopes. Gravitational lenses are a powerful tool in astrophysics and cosmology for studying the distribution of dark matter, the properties of galaxies and galaxy clusters, and the expansion rate of the universe. They also provide insights into the theory of general relativity and help to test the validity of alternative theories of gravity. Overall, gravitational lenses provide a unique window into the invisible and often mysterious components of the universe, leading to new discoveries and advancements in our understanding of the cosmos.