How do visitors know if a website is using SSL?
When a browser connects to a secure site, it retrieves the SSL certificate and checks to ensure the certificate has not expired, that a certificate authority the browser trusts issued it, and that it is being used by the website for which it was issued. If it fails on any of these checks, the browser will warn the end user. If it succeeds on all checks, the user will see indicators of a secure connection:
The beginning of the URL or web address changes from http:// to https://
In the web address bar, a padlock or other security icon will indicate a current SSL certificate is encrypting the site