how does a black hole work?

A black hole is a region of spacetime where gravity is so strong that nothing, not even light, can escape once it crosses the event horizon.

the event horizon

It is not a surface. Nothing marks the boundary; a falling observer would notice nothing special as they cross it, yet there is no way back.

gravity

Light passing nearby follows curved paths through warped space. Background stars smear into arcs, and some appear twice, once on each side of the hole.

time slows near the horizon

space

photon sphere

Seen from far away, a clock falling inward ticks slower and slower, and its light shifts toward the red until it fades from view.

Accretion disks are hot gas spiraling inward, glowing from friction long before it is gone.

singularity

Tidal forces stretch anything that falls in: the closer to the centre, the harder the pull on the near side versus the far side.

move your cursor. the hole follows.