Using secure Internet sites for transactions

From Microsoft Internet Explorer Help

Many Internet sites are set up to prevent unauthorized people from seeing the information that is sent to or from those sites. These are called "secure" sites. Because Internet Explorer supports the security protocols used by secure sites, you can send information to a secure site with safety and confidence. (A protocol is a set of rules and standards that enable computers to exchange information.)

When you visit a secure Web site, it automatically sends you its certificate, and Internet Explorer displays a lock icon on the status bar. (A certificate is a statement verifying the identity of a person or the security of a Web site. For more information, click Related Topics below.)

If you are about to send information (such as your credit card number) to an insecure site, Internet Explorer can warn you that the site is not secure. If the site claims to be secure but its security credentials are suspect, Internet Explorer can warn you that the site might have been tampered with or might be misrepresenting itself.