Coco (https://cocobubbletea.com/menu/) is a leading provider of various types of teas with cooked tapioca pearls. Tapioca is starch from a vegetable called cassava from South America.
https://en.m.wikipedia.org/wiki/Tapioca
Bubble tea is claimed to have been invented in Taiwan where someone decided to put tapioca into tea and it was a hit.
Nowadays it is very popular in cities. I'm Vancouver I've heard middle aged people complaining saying "a restaurant closed and another bubble tea shop is replacing it"
In Ireland loads of Asian female tourists are in the bubble tea shops and here in Vancouver it's similar with Canadian Asians girls and Asians girls being the target market.
https://en.m.wikipedia.org/wiki/Bubble_tea
I like bubble tea since I first tried it in Japan. I generally get milk tea with tapioca pearls 70% of the regular sugar amount and no ice. If you get ice 1/5 to 1/4 of the container will be ice and you will get a lot less tea and tapioca. You shake to mix the syrup/sweetness evenly within the drink and drink with a straw to get tea and tapioca at the same time. I don't get it that often but it's a guilty pleasure as I know there must be a lot of sugar used in it.