The idea originated from Dorsey's friend Jim McKelvey who was unable to sell some glass work to a customer because he couldn't accept a particular card being used.
Accepting credit card payments for something you're selling isn't always easy, especially if you are mobile like a tradesman, delivery service or a vendor at a trade show.
This latest invention uses a small scanner that plugs into the audio input jack on a mobile device.
It reads information on a credit card when it is swiped. The information is not stored on the device but is encrypted and sent over secure channels to banks.
It basically makes any mobile phone a cash register for accepting card payments.
As a payor, you receive a receipt via email that can be instantly accessed securely online. You can also use a text message to authorize payment in real time.
Retailers can create a payor account for their customers which accelerates the payment process.
For example, a cardholder can assign a photo to their card so their photo will appear on the phone for visual identity confirmation. Mobile devices with touch screens will also allow you to sign for goods.
There are no contracts, monthly fees, or hidden costs to accept card payments using Square and it is expected the plug-in attachment will also be free of charge.
A penny from every transaction will also be given to a cause of your choice.
As with Twitter, it's anticipated that Dorsey will direct the company based upon feedback from users.