You may have made sure that your websites have SSL enabled, and the pretty security padlock in your browser is green. However, you may have forgotten about HTTP’s little security man, HTTP Strict Transport Security (HSTS). What is HSTS, and how can it help keep your site secure? What Is HTTPS? Hyper Text Transfer Protocol Secure (HTTPS) is a secured version of a website (HTTP). The encryption is enabled using the Secure Sockets Layer (SSL) protocol and is validated with an SSL certificate.