Verifying What Integrity?

I’m almost embarrased to ash this, but I have tried 5 other A+ qualified people with no answer.
When using FDISK, and creating partitions, there is an intermediate step when the computer stops & “verifys disk integrity”. You see a percertage number on the screen count from 0 to 100% before you can complete the step you want. WHAT is the system checking? Is there any way to stop it? It’s really annoying. I promised my A+ students I’d find out about this. Someone please explain.
Thank You.