A standard-essential patent (SEP) covers technology that a published standard makes mandatory, so a compliant product cannot avoid it and the patent holder gains leverage no ordinary patent confers. To contain that leverage, standard-setting organizations such as ETSI and the IEEE require participants to license essential patents on fair, reasonable, and non-discriminatory (FRAND) terms, a promise the drafters never defined. This UpLaw reference explains what makes a patent essential, how the FRAND bargain works, and the three rival methodologies courts use to set royalties, then traces the field's foundational decisions in Microsoft v. Motorola and Huawei v. ZTE and the narrowing of the U.S. antitrust path after FTC v. Qualcomm. It maps the 2024-2026 realignment: England's interim-license doctrine, China's global rate-setting and the WTO's finding against its anti-suit injunctions, the Unified Patent Court's first FRAND ruling, the collapse of the EU SEP Regulation, and the unresolved fight over who in the supply chain takes the license as cellular spreads into cars, meters, and sensors. It closes with a phased negotiation playbook, a plain-language FAQ, and cross-references to related UpLaw resources.