Eugene's observations

Increasingly you may have noticed the square blobs of seemingly random spots popping up in advertisements. QR (quick response) codes allow a fairly large chunk of data to be rapidly and accurately transmitted to anyone with a suitable scanner - perhaps on your smartphone.

The data may be pure text, a voice message, a business card, WiFi details, a web hyperlink, geo location or any other burst of information. They are free to create at sites such as Zebra Crossing at http://zxing.appspot.com/generator or http://qrvoice.net and may contain advertising as long as the error correction rate is large enough. More error correction does lead to more complex codes though so choose M (15%) or Q (25%) rather than L (7%) or H (30%).

You can grab a free reader for most smartphones by visiting sites such as http://www.mobile-barcodes.com/qr-code-software/

Finally, here is a free offer for all my readers: