The holiday season provides you with some unexpected pleasures including having some time to browse TED and read about what amazing things are happening.

Now I usually wouldn’t make a fuss about some simple use of technology but the Captcha story delivered by Luis von Ahn amazed me and showed how tech can be used to such great effect.

About 200m people use Captchas each day (these are the things that present you with some distorted letters to type in to verify that you are human and not a computer). At 10 seconds for each one that is about 500,000 human hours a day.

So Luis, who was one of the people who invented the Captcha, thought this was a waste of time and so created Re-Captcha which he has used to identify words that OCR scanners that are digitising books can not recognise. ReCaptcha asks you to type in two separate words – one is used to verify the user and the second is used to get you to identify the word that the OCR missed – which it trusts you will do accurately. By offering the same missed words to a large number of people, ReCaptcha takes the most common response, assumes it is correct and passes it back to the book digitising process as a verified word.

So now ReCapture, using about 750m different users, is verifying 100m words a day, which equates to about 2.5m books a year – without the majority having a clue what they are doing.

Not sure how I feel about digitising books for Google (Google bought ReCaptcha) but think the lateral thinking here is just outstanding. He has taken it further and developed a language translation and language education service called Duolingo and the whole Captcha concept had spawned an Internet meme called CaptchArt. See above!