What makes it oolong
Withered leaf is shaken or tumbled repeatedly so that its edges are bruised while the centre stays intact. Oxidation then begins at the damaged margins and works inward, under the maker’s control, and is halted somewhere short of complete. A finished oolong leaf held to the light often shows this directly — a reddened border around a green middle. That is why oolong is not a uniformly half-oxidised leaf: it is a leaf oxidised heavily in one place and barely at all in another.
A short history
Oolong emerged in Fujian, with the Wuyi mountains and later Anxi as the two centres, and spread to Taiwan in the nineteenth century where it became the island’s signature product. Taiwan then drove the category’s most significant modern shift: the move towards very light oxidation and no roasting at all, which produced the green, floral, creamy style that now dominates what most people picture when they hear the word.
How it is made, and the two axes that matter
Wither, bruise repeatedly with rests between, fix, roll or shape, dry, and frequently roast. Two independent axes then determine what you get. Oxidation runs from very light (Baozhong, jade Tie Guan Yin, high-mountain Taiwanese) to very heavy (Oriental Beauty, which is oxidised nearly to black-tea levels). Roast runs from none to charcoal. A lightly oxidised, unroasted tea and a heavily oxidised, heavily roasted one are both oolong and share almost no sensory ground.
The four families worth knowing
Anxi ball-rolled oolong — Tie Guan Yin above all — is green, floral and creamy in its modern form. Wuyi rock tea is roasted, mineral and dark, with Da Hong Pao, Rou Gui and Shui Xian as its main names. Taiwanese high-mountain oolong is thick, sweet and unroasted, with a cooling finish practitioners call hou yun. Phoenix Dan Cong from Guangdong is the most aromatic and least forgiving, classified by which fragrance each bush resembles. Oriental Beauty sits apart: heavily oxidised, honeyed, and dependent on insect damage to the leaf.
Brewing: the category that most rewards gongfu
Ball-rolled oolong expands many times over, so use far less leaf than looks right and give the first steep long enough for the pellets to open — twenty to twenty-five seconds rather than the eight a rock tea wants. Roasted Wuyi teas need full boiling water and go flat below it. Dan Cong is the exception in the other direction: a few seconds too long and it turns genuinely bitter. Western brewing works but wastes the point, because a single long steep flattens a tea whose whole appeal is how it changes across a session.
Common misconceptions
That oolong is a midpoint on a green-to-black scale — it is a territory, not a point. That the dark colour of a roasted oolong means age, when roast and age are independent and roast character fades over a year or two of rest. That 'milk oolong' is flavoured with milk: genuine Jin Xuan is creamy from the cultivar, though much of what is sold under the name has indeed been artificially flavoured, so both readings are true of different products.