reCAPTCHA vs other captcha systems

Question

What is a good reason to choose reCAPTCHA over a well known and tested captcha generator on the server. Is it just philanthropy (helping with digitizing texts) or are there other good reasons.

Answer 1

reCAPTCHA is rather neat. Not only does it stop spammers but it helps digitize books. Each word that appears in the captcha has actually been scanned in from a book but sometimes the character recognition is off so the computer my save some gibberish of a sentence without knowing any better.

See the image off their site:

By making people type in what they think the word is, it helps create a digital copy of the book or word that was scanned with accuracy while at the same time checking what the user submit, comparing it to other's submissions, and determining if the user is human or not.

For that reason I use reCAPTCHA. I'm not just selfishly protecting my site, I'm providing a service for others.

Not only that but it's fairly simple to implement and provided by a reliable company (Google).