What is a black hole?

Laplace (1795) noted that a consequence of Newtonian gravity and Newton's corpuscular theory of light was that light could not escape from an object of sufficiently large mass and small radius.

Einstien (1915) publishes his theory of general relativity.

Schwarzschild (1916) derived a general relativistic solution for the gravitational field surrounding a spherical mass: Schwarzschild black holes.

Wheeler (1968) studies the problem of gravitational collapse - coins the term black hole.