Eli5: What exactly is auditing in accounting?

Question

I keep hearing this term from my accountant friend and have absolutely no idea what it means. I tried googling it but that just left me even more confused than I was.

In: 170

Answer 1

One very specific example:

Company: We spent a million dollars on office supplies.

Auditor: Checks receipts to make sure that they add up to a million dollars.