Deep Space Network is a series of communication antennas around the world used for communication with deep space spacecraft.
The Deep Space Network is a series of large antennas located in Madrid, Spain; Canberra, Australia; and California, USA. The three locations are arranged in such a way that once a spacecraft gets about 30,000 km away from Earth, it should always be in view of at least one of the locations (unless that view is blocked by the Sun, or some other planetary body).
The DSN network keeps space agencies in contact with the deep space spacecraft that have been launched, including New Horizons, Rosetta, Mars Reconnaissance Orbiter, and others.
On NASA's DSN NOW website, each antenna shows which craft, if any, it is communicating with.