Pietra Rivoli is an economist. She studies how countries buy and sell things. This is called trade. [1, 17]
Many years ago, Pietra studied a T-shirt. She started at a cotton farm. [8, 24] She followed the T-shirt to a store. This journey showed how global trade worked. Many countries worked together to make and sell one T-shirt.
Today, things are different. There are new rules for trade. These rules can make buying and selling things harder. Pietra now studies this new situation to understand it.