The practice started in the 1890s, at first given only to customers who paid for purchases in cash, to reward those who did not purchase on credit. It grew with the spread of chain gasoline stations in the early 1910s and then the new industry of chain supermarkets in the 1920s, and merchants found it more profitable to award them to all customers. Trading stamps were at their most popular from the 1930s through the 1960s.
In the United States, the most popular brand of trading stamps was "S&H Green Stamps", sometimes informally simply known as "Green stamps". Other larger brands included "Gold Bond Stamps" "Plaid Stamps", and "Blue Chip Stamps".
Merchants would pay a stamp company for the stamps, and then would advertise that they gave away stamps with purchases. The intent of this was to get customers to be loyal to the merchant, so that they would continue shopping there in order to get enough stamps to redeem it for merchandise.
Often customers would fill books with stamps, and take filled books to a stamp company store to redeem it for items. Books could also be sent to the stamp company in exchange for merchandise via mail order.
At the start of the 1960s, the S&H Green Stamps company bragged that it printed more of its stamps each year than the number of postage stamps printed by the US government. Starting in the 1970s trading stamps became less common.