Bubble tea was first dreamed up in a tea shop in the city of Taichung. A worker decided to drop some chewy tapioca balls (the kind used in puddings) into her cold milky tea. She liked it so much she shared the idea with the rest of the shop. Customers loved it. The shop started selling it, then other shops copied, and within a few years it was everywhere in Taiwan.
Tapioca pearls are made from a plant called cassava. The starch from the root is shaped into tiny balls and boiled. When they are cooked, they turn dark and squishy on the outside and chewy in the middle. They have almost no taste of their own - they soak up whatever drink they are sitting in.
Today, you can get bubble tea in hundreds of flavours - milk tea, fruit tea, matcha (green tea), taro, chocolate, mango, strawberry. Some shops let you choose how sweet you want it, how much ice, and what 'topping' you'd like (pearls, jellies, popping fruit balls, even pudding).
The straw is part of the magic. Bubble tea straws are extra-wide so the tapioca pearls can travel up. Lots of shops are now switching to reusable or paper straws to be kinder to the environment. Some cafés even hand out their own metal straws with the cup.