Hyper Text Transfer Protocol Secure (HTTPS) is a secure version of the Hyper Text Transfer Protocol (http). HTTPS allows secure ecommerce transactions, such as online banking.
Web browsers such as Internet Explorer and Firefox display a padlock icon to indicate that the website is secure, as it also displays https:// in the address bar.
When a user connects to a website via HTTPS, the website encrypts the session with a digital certificate. A user can tell if they are connected to a secure website if the website URL begins with https:// instead of http://.
i found a video to explain https step by step
http://www.securitytube.net/video/4037