Leidos Holdings Inc is a U.S. science, engineering, and information technology company that primarily serves government customers. It provides services and solutions in areas such as defense, intelligence, homeland security, civil, and health. Its largest customer is the U.S. Department of Defense, along with the intelligence community, the Department of Homeland Security, the Federal Aviation Administration, the Department of Veterans Affairs, and other federal, state, and local agencies, as well as some commercial and international clients. The company operates through segments including National Security and Digital, Health and Civil, Commercial and International, and Defense Systems. Revenue is generated mainly through long-term contracts for scientific, engineering, and technical services, systems integration, and IT support, with the majority derived from U.S. government agencies. Leidos is headquartered in Reston, Virginia.