What is a QR Code?

You have so far been hearing about Bar Codes which are nowadays found on almost all manufactured products. Bar codes store information about the item in vertical bars. A scanner at the modern shops can read those bars.
But now QR codes can be seen on billboards as well as in newspaper advertisements. A QR code can be read by an imaging device such as camera or smartphone. QR code stores information in black square dots on a square grid with white background.  These dots are arranged both horizontally as well as vertically. It was invented by Denso Wave in 1994 for automotive industry in Japan to track a particular vehicle while being assembled. But it is now used widely outside this particular industry.  
Merely by pointing a smartphone towards a QR Code on a billboard, a passeby in a car on a highway can access the product’s website and extract information.