spy

Spy is a person who secretly gathers information of value to a government, corporation, or organization. Spies aim to obtain intelligence through clandestine means while concealing their true purpose. They may operate as field officers, case officers, or assets, using cover identities and covert communication.

Espionage has a long history in warfare and diplomacy. In ancient times, rulers relied on scouts and couriers for information. Modern intelligence services emerged in the 19th and 20th centuries, expanding during World War II and the Cold War. In the information age, cyber espionage and signals intelligence have become increasingly important alongside traditional human intelligence.

Common activities include human intelligence (HUMINT), signals intelligence (SIGINT), imagery intelligence (IMINT), and open-source intelligence (OSINT). Tradecraft encompasses recruitment, handling of sources, maintaining cover, secure communication, and operational security. Spies may be described as assets, agents, or, in some cases, double agents who work for more than one side.

Spying is governed by national laws and international norms; those caught may face criminal penalties, expulsion, or diplomatic consequences. Notable intelligence agencies include the United States Central Intelligence Agency (CIA), the United Kingdom's Secret Intelligence Service (MI6), Russia's SVR and FSB, Israel's Mossad, and France's DGSE. Spies and their operations are also common in fiction, where dramatized portrayals may diverge from real-world practices.