Accounting
Audits
An independent examination of a business's financial statements by someone outside the company, giving outsiders a credible reason to trust numbers they had no part in producing.
Definition
An auditis an independent examination of a business's financial statements — and the internal controls behind them — performed by someone outside the company's own preparation process, to form a professional opinion on whether those statements fairly represent the business's financial position and results. It's not a guarantee that every number is perfectly correct; it's an independent, informed opinion that the statements are free of material misstatement.
Why this exists
Financial statements are prepared by the business itself — specifically, by the same management whose own performance those numbers reflect. Per Incentives, management often has a real incentive to make results look better than they actually are — a classic conflict of interest. Meanwhile, the people who most need the numbers to be trustworthy — investors deciding whether to buy stock, lenders deciding whether to extend a loan, tax authorities checking what's owed — weren't in the room for any of the business's transactions and have no independent way to verify the numbers themselves.
An audit exists to close that gap: an independent party, with no stake in making the numbers look good, examines the statements and the process behind them, and gives an outside opinion on whether they can be trusted. That independence is the entire point — it's what lets someone who has never met the business's management still have a credible basis for relying on its reported numbers.
Auditors don't check every single transaction a business makes — that would be far too costly and slow to be practical. Instead they focus on materiality: whether a potential error or misstatement is large enough that it could actually change a reasonable person's decision. This is a cost-benefit judgment, not a shortcut — spending unlimited effort chasing errors too small to matter to anyone's decision wouldn't make the audit more useful, just more expensive.
Worked example
A growing business asks a bank for a $500,000 loan. The bank has no way to independently verify the business's self-reported income statement and balance sheet — it wasn't present for any of the business's transactions.
If the business provides financial statements examined by an independent auditor, the bank has a credible, informed opinion from a party with nothing to gain from making the business look good — a real basis for trusting the numbers enough to extend the loan. Without that audit, the bank would have to either take the business's word for it, demand a much higher interest rate to compensate for the added uncertainty, or decline to lend at all.
Common misconceptions
“An audit guarantees a company's financial statements are completely accurate and free of fraud.”
Audits provide reasonable assurance, not absolute assurance. They rely on sampling and materiality thresholds rather than checking every transaction, and a well-hidden fraud can still slip through — audits reduce that risk substantially, but they don't eliminate it.
“The auditor and the accountant who prepared the financial statements are doing the same job.”
They're deliberately separate roles. Independence is the entire reason an audit is credible — an auditor reviewing statements they helped prepare would defeat the purpose.
“A clean audit opinion means the business is financially healthy.”
An audit checks whether the statements are presented fairly according to accounting rules, not whether the underlying business is doing well. A company can be in serious financial trouble and still receive a clean opinion, because the opinion is about accurate reporting, not good performance.
Also in the Glossary: Audit, Materiality, Reasonable Assurance