Oolongs are considered by most to be the most difficult to produce and the most interesting to taste. Unlike Green teas, which are not allowed to oxidize at all, and Black teas, which are 100% oxidized, oolongs are partially ozidized falling somewhere in between. Where they fall in between depends upon the tea, they can be very green to almost black
Taiwan, still referred to as Formosa in the tea world, is considered by many to be the champion of Oolongs. Prized Tiawanese Oolongs will often be drank in ceremonious style where the tea is brewed for many infusions for very short times. 30 seconds to 1 minute per infusion for up to 20 infusions depending upon the tea! The Taiwanese treasure their tea and with good reason (Tung Ting Oolong).
brewing: Due to the wide range of colors and shapes there is no one way to brew an oolong. Darker or flatter oolongs I will brew more like a black tea, 3-4 minutes at around 200 degrees. Greener or more curled, balled Oolongs I will steep shorter, 2-3 minutes at around 180 degrees for multiple steeps. High grade oolongs are meant to be steeped multiple times, make at least 3 or 4 cups from them and look for flavor changes as you go.