Oolong tea is, roughly speaking, a cross between green and black tea and is for that reason called 'semi-fermented'. It never becomes bitter, as it doesn't contain particularly much caffeine and tastes smoother than black tea but less fresh than green tea.
Best enjoyed chilled.
Data sheet
Nutritional content
Ingredients
Ingredients: Water, Oolong tea (43%), acidity regulator: E500, antioxidant: E300.
Oolong tea does not originate from Singapore.