"A QR code (abbreviated from Quick Response code) is a type of matrix barcode (or two-dimensional code) designed to be read by smartphones. The code consists of black modules arranged in a square pattern on a white background. The information encoded may be text, a URL, or other data.
Created by Toyota subsidiary Denso Wave in 1994, the QR code is one of the most popular types of two-dimensional barcodes. The QR code was designed to allow its contents to be decoded at high speed.[1]
The technology has seen frequent use in Japan and South Korea; the United Kingdom is the seventh-largest national consumer of QR codes.[2]"
This contains the URL of the main page of my blog.
Scan it with your smartphone (with some barcode reader app).
For example, by scanning this with the ShopSavvy app on my iPhone, I see the mobile version of my blog, as delivered by blogger.com.
Seeing it on mobile phone version gives you the option to see it anytime in web version.