A large social wasp, belonging to the order Hymenoptera, that builds nests made from chewed plants and wood. Hornets generally measure from a half-inch to an inch-and-a-half long. Their wings are reddish-orange in color, and their abdomens are orange with a brown stripe in the middle. The common European hornet has spread throughout much of the world, though they are close to extinction in Europe and parts of Canada.
Hornets are able to sting repeatedly and painfully, but they are not considered to be very aggressive insects. They may attack in a swarm if their nest is threatened, but it's believed that a hornet outside of the nest will always prefer to stay away from humans. They don't even tend to bother humans inside houses or on picnics -- their diet is limited, for the most part, to insects, spiders, and other wasps, so that big stinging bug hassling you for your peanut butter and jelly sandwich may actually be a yellowjacket.
Hornets are a protected species in Germany, and some areas of Europe have started hornet protection programs to help sustain the hornet population.
Research from http://www.allsands.com/Science/hornetinsect_abb_gn.htm