Most Americans have agreed to arbitrate hundreds of disputes without ever noticing, because the agreement was a paragraph in a document nobody reads. This article explains how arbitration clauses work, why courts enforce them so consistently, and what actually changes when a case goes to an arbitrator instead of a judge. It traces the Federal Arbitration Act from a 1925 statute about merchants to the doctrine that now governs employment, consumer, and nursing home disputes. It explains severability, delegation clauses, and why an argument that the whole contract is invalid usually goes to the arbitrator rather than the court. It covers the class action waiver, the mass arbitration strategy that turned the waiver into a liability, and the narrow grounds for vacating an award. It closes with what to do when you find one of these clauses in your own paperwork.