Tea from the Camellia sinensis plant ranges from light to dark; this spectrum also determines its flavor intensity and caffeine level.
At the far light end is White Tea, including White Peony and Silver Needle. White tea is picked when the leaves are still very young and have an almost fur-like coating still on them. White tea undergoes the least processing, has the lightest, most subtle flavor, and has no caffeine.
With slightly more caffeine, a bit of a richer color, more flavor, and less sweetness than white tea, is Green Tea. Famous green teas include Japanese Sencha and Matcha and Chinese Dragon Well 龙井 and Bi Luo Chun 碧螺春. Jasmine tea would also fall into this category as it is really jasmine-infused green tea.
Oolong Tea 乌龙, with a richer flavor, sandy or bronze color, and yet more caffeine is the next darker tea. It undergoes some oxidation/fermentation relative to the first two. Flavors can range from mildly sweet to bitter or astringent. Monkey-picked oolong, Iron Goddess 铁观音, and Big Red Rope 大红袍, with the former typically from Taiwan and the latter from the Chinese mainland, are the most well-known oolong teas.
The darkest teas undergo the longest oxidation periods, have the most caffeine, and also tend to be the most bitter–these include all types of Black and Pu’er Tea. However, sometimes black and pu’er teas are separated into categories labeled (1) fermented and post-fermented or (2) red and black tea, respectively. While there are many types of black teas sold internationally, pu’er is the only post-fermented tea available in the US, and it is the only dark tea that is never drunk with milk or sugar; it is also the first ingredient in Belight.