Types of Black Holes

Black Holes are the result of collapsed stars that are more than approximately 4 solar masses. Although stars, planets, moons, galaxies etc. all have thousands of distinguishing characteristics, black holes only have three (this was a theory entitled "Black Holes Have No Hair" created by John Wheeler).

The three characteristics are: mass, charge and angular momentum (the last is related to spin). A Schwartzschild black hole is a black hole with only mass, and neither of the other two characteristics. These black holes have an even gravitational well and a gravitational singularity shaped as a dot. Also, these black holes are perfectly spherical, and have a fixed event horizon radius. However, these holes are rare, and usually black holes are much more complex. More info on black holes can be found here, here and here.