Espionage (colloquially, spying) is the obtaining of information considered secret or confidential without the permission of the holder of the information. Espionage can be committed by an individual or a spy ring (a cooperating group of spies), in the service of a government, company or operating independently. The practice is inherently clandestine, as it is by definition unwelcome and in many cases illegal and punishable by law. Espionage is a subset of “intelligence” gathering, which includes espionage as well as information gathering from public sources.
Espionage is often part of an institutional effort by a government or commercial concern. However, the term is generally associated with state spying on potential or actual enemies primarily for military purposes. Spying involving corporations is known as industrial espionage.