Linked from
The 62 pages that link to Black hole, each with the reason it gives.
Stellar evolutionBroader topic: The most massive stellar cores can collapse into this endpoint.
GravityBroader topic: Black holes display gravity in its strongest known regime.
SpacetimeBroader topic: Its defining boundary is a causal feature of spacetime geometry.
X-ray binaryBroader topic: Black holes accrete companion-star matter without a solid surface.
StarBroader topic: The most massive stellar remnants can collapse into black holes.
GravitationBroader topic: Black holes exhibit gravitation in its strongest known regime.
RelativityBroader topic: Black holes are extreme solutions of general relativity.