Espionage is the practice of secretly gathering information, especially about governments, militaries, or organizations. When countries want to know what their rivals are planning, they sometimes send spies to collect classified information through espionage. The spies might photograph secret documents, listen to private conversations, or befriend people who have access to important information.

During World War II, both sides used espionage extensively. Spies worked undercover, pretending to be ordinary citizens while secretly sending information back to their home countries. Some famous spies, like British double agents, even pretended to work for one country while actually serving another. The intelligence they gathered helped leaders make crucial military decisions.

Espionage requires careful planning, disguises, code words, and often special training. Real espionage rarely resembles the flashy action of spy movies. Instead, it involves patient observation, careful note-taking, and maintaining a convincing false identity for months or years. Countries have special intelligence agencies, like the CIA in the United States or MI6 in Britain, dedicated to espionage and protecting against enemy spies.

Getting caught conducting espionage in a foreign country can carry serious consequences, since nations consider it a major crime.