If your neighborhood bakery now accepts credit cards as well as cash, you might have Square Inc. to thank for the convenience. Square provides hardware (a square-shaped card reader) and software to merchants and other service providers that enable them to accept credit card payments. The card readers attach to smartphones and tablets, providing a business with a low-cost point of sale system. Square’s software handles the backend of the transaction, making sure accounts square up between the merchant, the card company, the bank, and the consumer. Square charges a per-transaction fee (its standard rate is 2.75%). An early provider of mobile payment equipment and software, Square faces competition from established financial and technology companies.