process of validating a statement, item, or account. The accountant seeks and examines evidence in support of the item. The auditor also attempts to determine accuracy in the amount of the item by conducting auditing tests and procedures. Sometimes assurance need show only that the characteristic is within a prescribed range.
Banking:
Accounting: auditor's review of financial statements by comparing journal entries to actual documents, such as cancelled checks, copies of loan documentation, and so on.
sworn statements before a duly qualified officer that the contents of an instrument are correct.
Example: A tenant takes a landlord to court to recover a security deposit. The tenant files a claim describing the conditions under which the deposit is to be refunded and the manner in which the tenant complied with the conditions. The tenant then supplies verification of this description by a sworn statement.

