Espionage is the practice of obtaining confidential or sensitive information without the permission of the holder. This often involves covert operations conducted by governments or organizations to gather intelligence on rivals or enemies. Techniques can include surveillance, infiltration, and the use of informants, all aimed at gaining an advantage in political, military, or economic arenas. The history of espionage dates back centuries, with notable figures such as Mata Hari and Julius Caesar employing various tactics to gather intelligence. In modern times, espionage has evolved with technology, leading to cyber espionage, where hackers infiltrate systems to steal data. The implications of espionage can be significant, affecting national security and international relations.