Bubble tea (also known as pearl milk tea, bubble milk tea, or boba) is a Taiwanese tea-based drink invented in Tainan and Taichung in the 1980s. It became known as “bubble tea” because of the thick layer of foam that forms on top of the drink after it is shaken. Recipes contain tea of some kind, flavors of milk, and sugar (optional). Toppings, known as “pearls”, such as chewy tapioca balls (also known as pearls or boba), popping juicy balls, fruit jelly, grass jelly, agar jelly, and puddings are often added. Ice-blended versions are frozen and put into a blender, resulting in a slushy consistency. There are many varieties of the drink with a wide range of flavors.