Main features of a Schwarzschild black hole.
Credit: N. Rumiano
The simplest kind of black hole in theory but one that could never occur in the real universe. A Schwarschild black hole doesn't rotate (i.e. has zero angular momentum), has no electric charge, and exists in a spacetime with no other masses. It arises as an exact solution to Einstein's equations of general relativity worked out by Karl Schwarzschild in 1916.
There are three important features of a Schwarzschild black hole: