NASA means National Aeronautics and Space Administration
NASA is an independent agency of the United States federal government responsible for the civilian space program as well as aeronautics and aerospace research.
President Dwight D. Eisenhower established NASA in 1958 encouraging peaceful applications in space science. Since that time, most US space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA is also responsible for the training of astronauts.
Source: Wikipedia
NASA video
More about Nasa: