Question: Black holes are often referred to as what after Karl Schwarzschild who discovered this solution in 1916?
About the article "Black hole", section "Physical properties".

Candidate passages:
In Einstein's theory of general relativity, the Schwarzschild solution (or the Schwarzschild vacuum), is a solution to the Einstein field equations which describes the gravitational field outside a spherical mass, on the assumption that the electric charge of the mass, angular momentum of the mass, and universal cosmological constant are all zero.
The solution is a useful approximation for describing slowly rotating astronomical objects such as many stars, planets and black holes, including Earth and the Sun.
The solution is named after Karl Schwarzschild, who first published the solution in 1916.
According to Birkhoff's theorem, the Schwarzschild solution is the most general spherically symmetric, vacuum solution of the Einstein field equations.
A Schwarzschild black hole or static black hole is a black hole that has no charge or angular momentum.
A Schwarzschild black hole has a Schwarzschild metric, and cannot be distinguished from any other Schwarzschild black hole except by its mass.
The Schwarzschild black hole is characterized by a surrounding spherical surface, called the event horizon, which is situated at the Schwarzschild radius, often called the radius of a black hole.
Any non-rotating and non-charged mass that is smaller than its Schwarzschild radius forms a black hole.
The solution of the Einstein field equations is valid for any mass "M", so in principle (according to general relativity theory) a Schwarzschild black hole of any mass could exist if conditions became sufficiently favorable to allow for its formation.where "Q" represents the body's electric charge and "J" represents its spin angular momentum. 
The simplest static black holes have mass but neither electric charge nor angular momentum.
These black holes are often referred to as Schwarzschild black holes after Karl Schwarzschild who discovered this solution in 1916.
According to Birkhoff's theorem, it is the only vacuum solution that is spherically symmetric.
This means that there is no observable difference between the gravitational field of such a black hole and that of any other spherical object of the same mass.
The popular notion of a black hole "sucking in everything" in its surroundings is therefore only correct near a black hole's horizon; far away, the external gravitational field is identical to that of any other body of the same mass.
Solutions describing more general black holes also exist.
Charged black holes are described by the Reissner–Nordström metric, while the Kerr metric describes a rotating black hole.
The most general stationary black hole solution known is the Kerr–Newman metric, which describes a black hole with both charge and angular momentum.
While the mass of a black hole can take any positive value, the charge and angular momentum are constrained by the mass.
In Planck units, the total electric charge "Q" and the total angular momentum "J" are expected to satisfy
formula_1
for a black hole of mass "M".
Black holes saturating this inequality are called extremal.
Solutions of Einstein's equations that violate this inequality exist, but they do not possess an event horizon.
These solutions have so-called naked singularities that can be observed from the outside, and hence are deemed "unphysical".
The cosmic censorship hypothesis rules out the formation of such singularities, when they are created through the gravitational collapse of realistic matter.
This is supported by numerical simulations.
Due to the relatively large strength of the electromagnetic force, black holes forming from the collapse of stars are expected to retain the nearly neutral charge of the star.
Rotation, however, is expected to be a common feature of compact objects.
The black-hole candidate binary X-ray source GRS 1915+105 appears to have an angular momentum near the maximum allowed value.
Black holes are commonly classified according to their mass, independent of angular momentum "J" or electric charge "Q".
The size of a black hole, as determined by the radius of the event horizon, or Schwarzschild radius, is roughly proportional to the mass "M" through
formula_2
where "r"sh is the Schwarzschild radius and "MSun" is the mass of the Sun.
This relation is exact only for black holes with zero charge and angular momentum; for more general black holes it can differ up to a factor of 2.
The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is the radius of a sphere such that, if all the mass of an object is compressed within that sphere, the escape speed from the surface of the sphere would equal the speed of light.
An example of an object smaller than its Schwarzschild radius is a black hole.
Once a stellar remnant collapses below this radius, light cannot escape and the object is no longer directly visible.
It is a characteristic radius associated with every quantity of mass.
The "Schwarzschild radius" was named after the German astronomer Karl Schwarzschild who calculated this exact solution for the theory of general relativity in 1916. 
The Schwarzschild solution.
Since the field equations are non-linear, Einstein assumed that they were unsolvable.
However, in 1915 Karl Schwarzschild discovered an exact solution for the case of a spherically symmetric spacetime surrounding a massive object in spherical coordinates.
This is now known as the Schwarzschild solution.
Since then, many other exact solutions have been found. 
In 1916, Karl Schwarzschild obtained an exact solution to Einstein's field equations for the gravitational field outside a non-rotating, spherically symmetric body (see Schwarzschild metric).
Using the definition formula_1, the solution contained a term of the form formula_2; where the value of formula_3 making this term singular has come to be known as the "Schwarzschild radius".
The physical significance of this "singularity", and whether this singularity could ever occur in nature, was debated for many decades; a general acceptance of the possibility of a black hole did not occur until the second half of the 20th century.