How are caverns and sinkholes related?

Caves are underground. They are big long holes underground. Sometimes, for some unknown reason, the roof of the cave can no longer support the weight of the ground above it and the ground collapses down into the cave. The land sinks. It fills the hole. Where there was a cave, there is now solid ground. Where there was land, there is now a big hole. So, you have a sinkhole when the roof of a cave collapses.