A QR Code is a two-dimensional barcode that is readable by smartphones. It allows encoding over 4000 characters in a two-dimensional barcode. QR Codes may be used to display text to the user, to open a URL, save a contact to the address book or to compose text messages. “QR Code” is a registered trademark of DENSO WAVE INCORPORATED.
To read QR Codes with your smartphone, you need an appropriate software installed on your phone. For Android-based devices, you can use Barcode Scanner by ZXing. On iOS-Devices like iPhones, there are also QR Code readers available on the AppStore, for Example, i-nigma. On Firefox OS try QR Code Scanner. On Symbian devices, you can use Mobiletag barcodes reader for example.
If you use a modern web browser (recent versions of Firefox or Chrome) and have a webcam, there are websites that allow you to scan QR Codes with your web browser. You can use this to send a link from a phone to your desktop browser for example. There is no restriction of any kind. You can use these QR Code images for whatever you like, also commercially. Please note that the word “QR Code” is a registered trademark of DENSO WAVE INCORPORATED. If you want to use it, you have to add a trademark comment.
The content of a QR Code cannot be changed once generated. What is sometimes referred to as a Dynamic QR Code, is a QR Code pointing to a static URL that hosts the actual content (e.g. the real URL). The hosted content can be changed after the QR Code has been printed.