reCAPTCHA is a security service by Google that stops bots and other automated attacks. It is basically a test to tell computers if you are a human. Basically, you use reCAPTCHA to prove to Google that you are actually a human. Google is trying to fight bots and malicious attacks against websites. The goal of reCAPTCHA is to protect websites from bot attacks, like credential stuffing attacks, that can dramatically hurt your website.