Does this look familiar?  After filling out a form, you’ve likely been asked to read a distorted sequence of characters like this.

How many of you found it really annoying?  (Personally, I much prefer the CAPTCHA over the “select all the images that are cars/trees/bridges”.)

Invented in 1997, CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart.  CAPTCHAs are “a type of challenge–response test used in computing to determine whether or not the user is human.”

Mildly interesting, right?

But here is what you probably didn’t know.  If you’re decoding words with reCAPTCHA (like the image above), you are actually doing something good for humanity.  You’re solving a problem.

YOU are helping to digitize old books!

With reCAPTCHA you are given two words, one is a word the computer knows the answer to, the other word is a word that needs to be digitized.  If you get the test word correct, the computer assumes you also got the other word correct.  Does this mean all the responsibility of correctly decoding a word is falling on your shoulders?  Nope.  Once ten people agree on the new word, the computer digitizes that word.

I find this fascinating!

Now, the same brilliant guy (Luis von Ahn) who came up with CAPTCHA/reCAPTCHA also created Duolingo.  You get to learn a language for free, but what you’re also doing is helping to translate the web!

Ok, I’ve basically given away all the exciting parts of Luis von Ahn’s TEDtalk, but I highly suggest you take some time to watch it.  It’s 20 minutes, but remember that you can watch it in fast-forward mode (just click on the little cogwheel in the lower right hand corner and pick your speed).