Safari 5.1 (OS X Lion): Identify secure websites
When you use a website that handles private or financial information, make sure the website is secure.
Look for a lock icon
A lock icon at the top of the Safari window or in the address field means that the website has a certificate. This indicates to Safari that it’s a legitimate website and that information you exchange with it will be encrypted.
To view the contents of a website’s certificate, click the lock icon.
For more information about certificates, see:
Use a secure connection, if available
If the website is not secure, you may have been given a choice between a secure and an insecure connection when logging in to the site. Go back to the page where you logged in and check for a link to a secure login. Even if you don’t plan to view private information, it’s best to use a secure login whenever possible to ensure that your login information and any other information you send is encrypted.