Most debt collection lawsuits end in default judgment, and most of those defaults are entered against people who had a defense. This article explains why, and what changes when the consumer shows up. It traces the debt-buying industry from charge-off through portfolio sale to the courthouse, and explains what the buyer actually purchases — usually a spreadsheet row, not a file. It covers the two proof problems every debt buyer faces, standing and admissibility, and why an answer that denies the debt forces the plaintiff to solve both. It explains the Fair Debt Collection Practices Act's validation notice, the thirty-day window most consumers waste, and the modern regulation that governs contact frequency and electronic communication. It covers time-barred debt, revival by partial payment, and Rotkiske's holding on when the clock starts. It covers credit reporting, the dispute mechanism that creates the claim, and why disputing with the furnisher rather than the bureau destroys it. It covers judgment enforcement, exemptions, and what it means to be judgment-proof. A fictional case runs throughout.