Since the early 1990's, a large number of new data sets have become available as a result of both the highly successful ISTP satellite missions and extensive ground-based observations. The advance of computer networks has led to the effective exchange and treatment of these data sets, improving our ability to study dynamic behavior in the Earth's electromagnetic environment. Attempts have also been made to compare in an orchestrated fashion computer simulations with realistic boundary conditions resulting from in-situ observations in space. The Fourth International Conference on Substorms...