The federal government buys hundreds of billions of dollars of goods and services a year, and the rules for selling to it look nothing like commercial contracting. This article explains how the system actually works, starting with the two ways the government buys — sealed bidding and negotiated procurement — and why understanding the difference determines whether a company can win. It covers the small business programs that reserve a substantial share of federal spending, what a solicitation is really telling a bidder to do, and how proposals are evaluated on price and past performance and technical approach. Separate parts address bid protests at the agency, at the Government Accountability Office, and in the Court of Federal Claims, including the automatic stay that makes timing decisive. Later parts cover performance: changes, delays, requests for equitable adjustment, claims under the Contract Disputes Act, and the two very different kinds of termination. A final part addresses the compliance risks that end companies — False Claims Act liability, suspension, and debarment. Examples run throughout.