A rift valley is a lowland region formed by the movement of tectonic plates. It occurs when the Earth's crust stretches and fractures, creating a long, narrow valley. These valleys are often characterized by steep sides and can be found in various parts of the world, such as the East African Rift. Rift valleys can lead to the formation of lakes, such as Lake Victoria, and are often associated with volcanic activity. The geological processes that create rift valleys can also result in earthquakes, making them important areas for studying tectonic activity and Earth's geological history.