Once a black hole has formed, it can continue to grow by absorbing additional matter. Any black hole will continually absorb interstellar dust from its direct surroundings.
A simple black hole
The term "Black Hole" comes from the fact that, at a certain point, even electromagnetic radiation (e.g. visible light) is unable to break away from the attraction of these massive objects. A black hole would thus appear black from the outside. (However, gas around a black hole can be very bright).
In My next posts I will discuss the other features oh black holes in our space.