What is "recaptcha"

reCAPTCHA is a new Google tool to protect your site from spammers and bots. It comes from a new idea, because until then the Caps were seen more as an obstacle than a helper by users. With reCAPTCHA this is different, because all the user needs to do is click on a checkbox, confirming that it is not a robot.

With reCAPTCHA, all the user needs to do is click one checkbox, confirming you’re not a robot. This way everyone wins, the user has faster access to the desired information, and you keep unwanted visitors from your site.

To learn how to implement reCAPTCHA, see this answer (which served as the source for editing this wiki).