reCAPTCHA is a CAPTCHA system that enables web hosts to distinguish between human and automated access to websites. The original version asked users to decipher hard to read text or match images. Version 2 also asked users to decipher text or match images if the analysis of cookies and canvas rendering suggested the page was being downloaded automatically. Since version 3, reCAPTCHA will never interrupt users and is intended to run automatically when users load pages or click buttons. reCAPTCHA is owned by Google.
