Answer:
When a giant star collapses, there is a possibility that it could form a singularity, a single point in space with infinate mass, zero volume, and infinate gravity. We can't see Singularity because they are covered by a dark region called the Event Horizon. Because it is dark and things seem to "fall" into the dark region, it was dubbed a "black hole". We now know that black holes have incredibly strong gravitational pulls, so strong that not even light can escape. The singularity pulls everything within its gravitaional reach towards it. When an object reached the event horizon(black hole), it disappears. What is theorized is that the singularity's gravitional pull is so massive that molecules are broken up into the smallest sub-atomic particles. Everything basicaly "dematerializes" at the event horizon, creating the dark region that we see.