A Guide to Adventure Bikes

What's an "adventure bike"? Any motorcycle that takes the rider on an adventure (rather than say short/routine trips). Typically adventure bikes are a blend of dirt and road motorcycle. It seems as though any motorcycle can qualify to be an adventure bike, but motorcycle manufacturers have made specialized machines just for "adventures". To me there's three general categories that adventure bikes fit into; oversized dirtbikes, dirt-worthy street bikes, and the BMW GS. I'm going to cover all three, in three quick and dirty features.