We all use bar codes to buy things. Now small businesses are using them to sell things.

Quick response codes, known as QR codes, are those bizarre looking, black-and-white gridded squares you see on posters and signs. They render information in a way that digital devices can easily understand. QR codes connect names, numbers and other data to physical objects using the camera on a smart phone or other portable device.

QR codes are popping up not only at hipster events like the annual South by Southwest conference and festival in Austin, Texas, but also in mainstream corporate marketing. TAG Heuer, Macys and the car maker MINI now sell using QR codes.

Until recently, it was difficult for small firms to use bar codes as big firms do to connect promotions, company information and other marketing tools to business cards, signage and other business collateral. Scanning, creating and matching the back-end digital infrastructure of QR codes was a complex and expensive proposition.

No more. Several vendors offer sophisticated scanning tools, content-creation systems and even integrated marketing platforms.