Google has re-introduced a new CAPTCHA system with full makeover called “reCAPTCHA” The new system will allow people into websites with only a single click. Users will now be presented with a checkbox that will say “I’m Not a Robot” next to it. The old system will remain active, and many sites may decline to upgrade, but the overall effect will be a great effect on users. Google is encouraging every websites that uses CAPTCHAs to switch to this new system.
Source: https://thehackernews.com/2014/12/Google-reCAPTCHA-code-in-PHP.html