Espionage is the crime of spying on the federal government and/or transferring state secrets on behalf of a foreign country. If the other country is an enemy, espionage may be treason, which involves aiding an enemy. The term applies particularly to the act of collecting military, industrial, and political data about one nation for the benefit of another.
Espionage is a part of intelligence activity, which is also concerned with analysis of diplomatic reports, newspapers, periodicals, technical publications, commercial statistics, and radio and television broadcasts. In recent years, espionage activity has been greatly aided by technological advances, especially in the areas of radio signal interception and high-altitude photography.