Cooper Hewitt says...
The Defense Advanced Research Projects Agency (DARPA) is an agency of the US Department of Defense responsible for the development of new technologies for use by the military. DARPA has been responsible for funding the development of many technologies which have had a major impact on the world, including computer networking, the Internet, and NLS, which was both the first hypertext system, and an important precursor to the contemporary ubiquitous graphical user interface.
DARPA began as the Advanced Research Projects Agency (ARPA) created in 1958 by President Dwight D. Eisenhower for the purpose of forming and executing research and development projects to expand the frontiers of technology and science and go beyond immediate military needs. The administration was responding to the Soviet launching of Sputnik, the first artificial Earth satellite, in 1957. ARPA's mission was to ensure that US military technology be more sophisticated than that of the nation's potential enemies.
ARPA was renamed to "DARPA" (for Defense) in March 1972, then renamed "ARPA" in February 1993, and then renamed "DARPA" again in March 1996. DARPA is independent from other more conventional military research and development and reports directly to senior Department of Defense management. DARPA focuses on short-term (two to four year) projects run by small, purpose-built teams.