Hypertext Transfer Protocol Secure or in short, HTTPS is a secure hypertext protocol communication method that allows transferring data securely between two parties.
HTTPS was originally developed by Netscape and was published with SSL 1.0 in 1994 in the Netscape browser.
It is standard for almost every website or other communication over the internet today. For HTTPS to work for your domain, the owner of the domain name has to certify that he truly is the owner. This is done via an SSL certificate.
When a domain has the correct SSL certificate installed, each client can determine by checking the certificate with a set of trustworthy sources if the connection is secure.
With the introduction of Let's Encrypt (that allows us to generate free SSL certificates automatically) the internet got much more secure because now there is no excuse to not offer HTTPS for any website on the internet.