The EUREF Permanent Network (EPN) is a voluntary federation of over 100 self-funding agencies, universities, and research institutions in more than 30 European countries. They work together to maintain the European Terrestrial Reference System (ETRS89) which is the single Europe-wide standard coordinate reference system adopted by the European Commission (ref COGI action decision 2003 - F/GIS/69/EN). The network is operated under the umbrella of the IAG (International Association of Geodesy) Regional Reference Frame sub-commission for Europe, EUREF. Next to its key role in the maintenance of the ETRS89, the EPN data are also used for a wide range of scientific applications such as the monitoring of ground deformations, sea level, space weather and numerical weather prediction.