Self-checkouts (SCOs), also known as assisted checkouts (ACOs) or self-service checkouts, are machines that allow customers to complete their own transaction with a retailer without using a staffed checkout. When using SCOs, customers scan item barcodes before paying for their purchases without needing one-to-one staff assistance. Self-checkouts are used mainly in supermarkets, although they are sometimes also found in department or convenience stores. Most self-checkout areas are supervised by at least one staff member, often assisting customers to process transactions, correcting prices, or otherwise providing service.
As of 2013, there were 191,000 self-checkout units deployed around the globe, and by 2025, it is predicted that 1.2 million units will be installed worldwide. It has been estimated that "the self-checkout system market in the U.S., which accounts for 41% of the global market, reached $1.4 billion in 2021."