Https means Http over secure socket layer (SSL). When ever a client sends a request, first server establishes SSL Connection to the client and client certificate will be installed to the client side.
From the browser, entire information will be transmitted across SSL by encryption,hence we can achieve data-integrity and confidentiality.
- This is most secure authentication.
- It is very costly to implement and maintain, it requires a certificate from third party certification authority like VeriSign.