What's at the bottom of a black hole?

The singularity at the bottom of a black hole is a point of infinite density and infinite curvature in space-time, where the laws of physics as we know them break down. This makes it impossible to know for certain what exists at the bottom of a black hole, as our current understanding of physics cannot fully describe the conditions within a black hole.

In summary, at the bottom of a black hole lies a point of infinite density called the singularity, where the mass of the black hole is confined to and has infinite curvature in space-time, making it impossible for anything to escape from it, including light.

For more details, check out the complete article:
https://sciquest.org/whats-at-the-bottom-of-a-black-hole/