Discovery consumes the majority of the budget and calendar in most federal civil cases, and it is where avoidable errors most often turn into sanctions, waivers, and lost evidence. This UpLaw research guide maps the full architecture of federal discovery under the Federal Rules of Civil Procedure—public records and FOIA, initial disclosures, interrogatories, requests for production, requests for admission, depositions, and third-party subpoenas—along with the objection practice, privilege doctrines, privilege logs, and e-discovery protocols that surround each tool. It explains proportionality under Rule 26(b)(1), the certification duty of Rule 26(g), the December 1, 2025 amendments that move privilege-log planning to the front of a case, and the complete Rule 37 sanctions apparatus, including the intent line that governs ESI spoliation. A single invented dispute runs throughout to make the doctrine concrete, and every rule is grounded in primary authority and controlling case law. The guide is written to be useful to a judge, a seasoned litigator, and a newer practitioner alike, and reflects the rules as amended through late 2025.