LOFAR is the LOw Frequency ARray for radio astronomy. LOFAR was built by ASTRON and is operated by ASTRON's Radio Observatory. The project is based on an interferometric array of radio telescopes in 40 stations distributed across the Netherlands, five stations in Germany, and one each in Great Britain, France and Sweden. Further stations may also be built in other European countries. The total effective collecting area is approximately 1 square kilometer, with the data processing performed by a Blue Gene/P supercomputer situated in the Netherlands at the University of Groningen.