# What is Event Horizon of a Black Hole? [closed]

The boundary of a black hole is said to be surrounded by event horizon - the point of no return! What is its significance in terms of general relativity?

• The question "What is its significance in terms of general relativity?" is both too broad and out of scope for this site (belongs on Physics.SE). Could you clarify exactly what information you are looking for? – called2voyage Feb 25 '14 at 17:28
• What I mean to say is, how are the characteristics of event horizon related to Space-Time? – Spacetrekker Feb 26 '14 at 13:45

It is exactly the point of no return for light. In other words, it is the point (actually more like a sphere) in which the escape velocity from the Black Hole gravity reaches $c$.