QR codes

Visit my LinkedIn profile by scanning this QR code!

What are QR codes?
The "QR" in QR codes stands for "Quick Response." QR codes are a type of barcode invented in 1994 by the Japan-based Denso Corporation in an effort to store more information than the usual vertically striped UPC barcodes:

A QR code involves a square grid of black and white bits, and can either range from a 1x1 square, to a 40x40 grid. The larger the grid, the more information can be encoded. A QR code is essentially a method of information compression. Although it was initially used to store information on manufactured components by Denso, after its release to the public, QR codes are now often used to store URLs to websites or URLs that allow access to applications. 

There are four levels of error correction possible for QR codes: Low (7% codeword restoration rate), Medium (15% codeword restoration rate), Quartile (25% codeword restoration rate), and High (30% codeword restoration rate). For example, with a Quartile QR code, as long as more than three-fourths of the QR code is not damaged, the QR code will still work. The general way to think of it is: "as long as the damaged fraction of the QR code doesn't exceed the codeword restoration rate, the QR code will still work."

How do you use a QR code?

1. Find a QR code scanner for your phone, be it a Blackberry, an Android, or an iPhone.
2. Scan the barcode.
3. See where the barcode takes you!