By using this code we can simply add captcha to our websites. You have to add your site key to the data-sitekey property generated by google captcha. Google provides this technology to add your website to block spammers and bots that try to automatically get email addresses or try automatically sign up for or make use of Web sites, blogs or forums. The acronym of CAPTCHA is a Completely Automated Public Turing test to tell Computers and Humans Apart.
<title>How to add re CAPTCHA security to your website</title>
<script src="https://www.google.com/reCAPTCHA/api.js" async defer></script>
<form action="?" method="POST">
<div class="g-reCAPTCHA" data-sitekey="your_site_key"></div>
<button type="submit" class="btn btn-success">Submit</button>
It will help you to protect your site from spammers.