[url=http://www.google.com/recaptcha/learnmore]...consider that you are actually transcribing an old book.[/url] [quote]About 200 million CAPTCHAs are solved by humans around the world every day. In each case, roughly ten seconds of human time are being spent. Individually, that's not a lot of time, but in aggregate these little puzzles consume more than 150,000 hours of work each day. What if we could make positive use of this human effort? reCAPTCHA does exactly that by channeling the effort spent solving CAPTCHAs online into "reading" books. ... reCAPTCHA improves the process of digitizing books by sending words that cannot be read by computers to the Web in the form of CAPTCHAs for humans to decipher. More specifically, each word that cannot be read correctly by OCR is placed on an image and used as a CAPTCHA. This is possible because most OCR programs alert you when a word cannot be read correctly.[/quote]Hey! Well done you. You're part of a collaborative effort to digitize about 2.5 [i]million[/i] books per year. This is the reason Captcha gives you two words. One is a word the system knows (so it can judge whether you got it correct), the other is one it doesn't. When 10 or more people agree on a word, that's a new word transcribed. Pretty nifty, eh?