Audit
An audit can be defined as an activity that usually involves an inspection that is carried out within the company, to ensure compliance or certain processes or procedures. For example, you may audit to verify that you have paid out all your employees correctly and accurately while processing payroll, so you may check your payroll reports, with amounts that have been debited from the actual bank account.
Similarly, many systems have audit trail which has various checks and balances to ensure the integrity of the systems and processes used, within the organization.