The common definition of a black hole as a point singularity surrounded by an event horizon refers to *nonrotating* (Schwarzschild) black holes. According to classical physics, a zero-dimensional mathematical point cannot have angular momentum or demonstrate rotaton. The simplest shape that can support rotation is a two-dimensional ring, and a Kerr black hole is simply a rotating black hole, which contains a ring-shaped singularity.

Unlike nonrotating black holes, Kerr black holes have two event horizons. The outer event horizon corresponds to the event horizon of a nonrotating black hole, but the inner event horizon also forms a boundary. Upon crossing the inner event horizon, an object would escape the black hole, but it would come out "elsewhere," possibly in a distant part of the universe or in a different universe altogether. It is geometrically possible that two Kerr black holes could be connected, forming a two-way wormhole, although any processes by which such a connection could be created are purely hypothetical.

It's a region in space where the gravitational field is so strong that nothing can escape it's pull.