ThredUP tells it's readers what they are looking for and they can send in items matching that description. After an item is accepted for re-sale ThredUP will pay the sender in the form of cash or a store credit if it is sold. They also give users a discount for simply donating their old clothes. This makes buying clothes even cheaper when you replace an item for something newer. Because customers who choose to sell through ThredUp can mail in their clothing for cash, and buyers can purchase used clothing for bargain basement prices, it's a win/win for all.