A Kerr black hole is a type of rotating black hole that is described by the Kerr solution to Einstein's equations of general relativity. Unlike non-rotating black holes, which are spherical, Kerr black holes have an oblate shape due to their rotation. This rotation causes the black hole to drag spacetime around with it, a phenomenon known as frame dragging. Kerr black holes are characterized by two main properties: mass and angular momentum. They can also have an event horizon, which is the boundary beyond which nothing can escape, and an inner Cauchy horizon. These features make Kerr black holes important for understanding the dynamics of rotating objects in the universe.