Square is a point-of-sale system for sellers with physical or online stores. Launched in 2009 by Block, Inc. (formerly Square, Inc.), it enables merchants to accept card payments and manage business operations. As of 2024, Square is the U.S. market leader in point-of-sale systems, serving 4 million sellers and processing $228bn annually.

Square is cloud-based and offers both physical devices, which read payment card