The game of checkers dates back several centuries at least, and historical records show that by the 1600s, there were checkers strategy books in circulation. Over the years, checker pieces have been made of colored stones, painted wood, and even dyed slices of corncob. Boards have been scratched on the ground, carved in wood, or, more recently, printed on cardboard or plastic. In the 19th century, machine-made wooden pieces replaced hand-carved options. Then in the 20th century, plastic sets became nearly ubiquitous. Checkers remains a popular game today. In fact, Pressman Toys, one of the leading manufacturers of checker sets, estimates that they have sold more than 25 million sets since their founding in 1922! Today, there are a variety of checker sets on the market, including computer game versions, magnetic travel-sized sets, and even jumbo sets.