An audit report is one page and it is the most misunderstood document in commerce. This article explains what an auditor actually promises, why reasonable assurance is not certainty, and why the expectation gap between what the public believes an audit does and what it does is the source of nearly every accounting liability dispute. It covers who may sue an accountant and the privity rules that decide it, the very different exposure created by audits, reviews, compilations, and tax work, and the scienter requirement that defeats most federal securities claims against auditors. It traces the doctrine from Ernst & Ernst through Central Bank, Stoneridge, and Janus to explain why secondary actors are so hard to reach. It covers the workpaper and privilege rules that surprise clients, the tax preparer penalty regime and its practice standards, the regulatory layer applying to public company audits, and the engagement letter terms that decide claims years before they arise.