LOFAR is the world’s largest and most sensitive radio telescope operating at low radio frequencies, between 10 and 240 MHz. It is a distributed research infrastructure that consists of multiple antenna stations, geographically distributed across Europe, all driven in software and with powerful computing and massive data storage at several distributed data centres. Jointly operated, this forms a unified, highly agile and capable observing and data processing system. With a sensitivity more than a hundred times better than any previous telescope at these frequencies, unparalleled image resolution across a large field of view, and capabilities to observe simultaneously in multiple directions, LOFAR is by far the most powerful low frequency telescope on the planet, and is revolutionising our view of the low-frequency radio universe. LOFAR was originally developed by NWO-I/ASTRON, the Netherlands Institute for Radio Astronomy, which now hosts LOFAR ERIC and furnishes most of the LOFAR ERIC operational services. LOFAR ERIC is jointly funded by its members and partners, who are collectively implementing a major upgrade (LOFAR2.0) for substantially improved and extended scientific research capabilities.