Blitzortung.org constitutes a network for lightning data over Central Europe. This is a non-commercial project free for everybody. People who want to participate need a lightning detector with directional determination of lightnings and a personal computer permanently connected to the Internet. The lightning data will either be send to our server or fetched from the contributing stations in short time intervals. The collected data will be stored at our server and used for computing the exact locations of lightnings by a triangulation. All computed coordinates of sferics are accessible from the server for everybody and can be used for any non-commercial further processing. This allows you, for example, to develop own applications for displaying lightning data over Central Europe on the Internet. In contrast to other lightning networks, the data we present is real time and for free.