Environmentally friendly, without paper, there is much to discover!
PS: QR codes can encode all kinds of information. To decrypt them, you need a phone with camera and QR reader. Such apps are on all smartphone in different versions. Read the square QR code with the phone’s camera, while the app is running. Once the code has been detected, the program decrypts the content of the image, displays the result on the screen and starts the stored action – for example, by opening the website, whose link was stored in the QR code.