The highly variable conditions in the Earth-related space environment, including the Sun, the interplanetary medium and the coupled magnetosphere-ionosphere-atmosphere system, are collectively known as space weather. In the recent past we have experienced that space weather influences the performance and reliability of space- and ground-based technological systems. Although several technological impacts of space weather had been known for some time, it was not before the 1990s that their significance increased dramatically and their severity became apparent.