To prove you’re human, Google’s reCAPTCHA system prompts users to hold down a button on their screen for a few seconds. This test helps the company determine that the user is indeed a person and not a computer program or bot. The reference ID provided can be used to verify the request, but it’s not necessary for the test itself. By holding down the button, users demonstrate their ability to interact with the digital world in a way that’s unique to humans. This process ensures that only legitimate human interactions are allowed on Google’s services and helps protect against automated threats.
Source: https://www.sfgate.com/shopping/article/how-to-reduce-microplastics-in-your-home-life-20772188.php