A QR code is a kind of label which can be read by a computer. You can see an example below.
In function they are very similar to the barcode you'd find on most items for sale in a store. Just as the cashier scans an item and the computer decodes the item's product number, your iPhone, iPod touch or other smartphone can scan a QR code and decode it into a string of letters and numbers.
Often a QR code contains a URL for a website, to make it easy to visit that site on your smartphone -- no typing required. QR codes are commonly used in a variety of places, including magazines and poster advertisements.
In That Box lets you print* or email QR codes on labels and inventories. Once you've set up In That Box and labeled your containers, you can scan the QR code** on any container or location to instantly view a list of what's inside, even if you've edited In That Box after the QR code was created.
*Printing requires an AirPrint-compatible printing set up.
**Scanning QR codes requires an auto-focus camera, e.g. iPhone 3GS or higher.