Jack Dorsey is best-known as the creator of Twitter. However, it is his most recent venture — Square, Inc. — that is impacting the payment-processing system in retailing. The firm is a mobile payment-processing provider.

Here’s how Issie Lapowsky, writing for Inc. describes the new company: “Square introduced the Card Reader, a 1-inch-square white dongle that plugs into a headset jack and, voilà, turns any iPhone, iPad, or Android phone or tablet into a credit card processor. Today, more than three million merchants are using the Card Reader to process $12 billion a year in transactions. The reader, which is free to order on the Square site, connects to Square Register, a souped-up point-of-sale app that replaces the traditional cash register, allowing customers to pay with cash or swipe a credit or debit card and sign on the screen with a finger. In 2011, Square launched a consumer-facing app, Square Wallet, that allows customers to walk into a store and pay by just saying their names. It’s being used at more than 250,000 locations in the U.S. and Canada.”

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