Forty Years

QR Codes can be used by a mobile device to jump straight to a web page. In the "Forty Years" book, QR Codes are used to direct you straight to the images for that chapter - that is all.

You can just as easily jump to the chapter using the website menu in the Photos section.

On an Android phone you can use Google Googles - there that covers 80% of the smartphone sales (as of Q3 2013). All the other minority smartphones should have QR Code readers available.

For more details on QR Codes have a look at Wikipedia: http://en.wikipedia.org/wiki/QR_code#Mobile_operating_systems