Federal agencies write far more binding law than Congress does, and the process by which they do it is open to anyone with an internet connection and something useful to say. This article explains how a rule is actually made — the proposal, the comment period, the response to comments, and the record that determines whether the rule survives — and why the comment nobody reads is frequently the one that decides the litigation. It explains the difference between a legislative rule, an interpretive rule, and a guidance document, and why agencies care intensely about the distinction. It covers judicial review: who has standing, when a rule is ripe, what arbitrary and capricious review actually requires, and what changed when the Supreme Court ended deference to agency interpretations of ambiguous statutes. Readers finish knowing how to write a comment that matters and how to evaluate whether a rule can be challenged.