A massive star that has collapsed to such a small size that its gravitational force is so strong that not even light can escape from its 'surface'.
First law of black hole dynamics
For interactions between black holes and normal matter, the conservation laws of mass-energy, electric charge, linear momentum, and angular momentum, hold. This is analogous to the first law of thermodynamics.
A rotating black hole.
Schwarzschild Black Hole
A nonrotating, spherical black hole that has no electric charge.
Second law of black hole dynamics
With black-hole interactions, or interactions between black holes and normal matter, the sum of the surface areas of all black holes involved can never decrease. This is analogous to the second law of thermodynamics, with the surface areas of the black holes being a measure of the entropy of the system.