Working papers have been written to explain how a bank or company is audited, but the reality is often quite different.
This is because audit is so different from a bank, and there is a lot of work done by auditors.
To help make this clearer, this is our list of the best and most useful audit tools.
If you need a more in-depth guide to auditing, we recommend The Audit Guide from Audit.co.uk.
This article is part of the BBC Future series on managing your financial life.