Check this site.
http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html
1. What is a Black Hole,what are its parts and what does it do?
2 answers
A black hole is a body of matter that is so dense that its gravitational attraction will not let light or anything else escape. Matter that gets sucked inside it disappears from the universe forever, but adds to the mass of the black hole.
Black holes are sometimes formed when very heavy stars run out of fuel and collapse due to their own gravity. This is the cause of some supernova events. The typical diameter of a black hole formed in this manner is only a few kilometers. According to Stephen Hawking, smaller "mini" black holes may also exist, but none have so far been observed.
Black holes are sometimes formed when very heavy stars run out of fuel and collapse due to their own gravity. This is the cause of some supernova events. The typical diameter of a black hole formed in this manner is only a few kilometers. According to Stephen Hawking, smaller "mini" black holes may also exist, but none have so far been observed.