Rotating black holes, also known as Kerr black holes, are a type of black hole that spins around an axis. This rotation causes the black hole to have a unique shape, making it slightly flattened at the poles and bulging at the equator. The spinning motion affects the space around it, creating a region called the ergosphere, where objects can be influenced by the black hole's rotation without falling in. These black holes are formed when massive stars collapse at the end of their life cycle, and their angular momentum is conserved. The rotation can lead to interesting phenomena, such as the ability to extract energy from the black hole, a process known as Penrose process.