Web browsers can operate in “normal” mode and in “secure” mode. You can tell which mode your browser is in by looking at the toolbar on your browser window (top of browser for Netscape, bottom of browser for IE). If you see a broken key, or an open padlock, you are in normal mode. If the key is whole, or the padlock is closed, you are in “secure” mode.
     When you surf the Net in “normal” mode, all of the information you type into your browser and all the information the Web site sends to you are visible to eavesdroppers. When your browser is in “secure” mode it encrypts all the information between itself and the server. Encrypted information looks like meaningless garbage to eavesdroppers, so your personal information is secure.

     A digital certificate contains the name of a company, Web site or individual, along with a cryptographic key that can be used to encrypt information that must be sent to that individual. When your browser switches into secure mode, it asks the Web site to present its certificate. The browser decides whether or not it trusts the certificate by looking at who issued it. If the browser trusts the certificate (as it does those issued by Thawte), then it will encrypt all communications with that Web site, using the cryptographic key in the certificate.
     Digital certificates are issued by an independent and trusted third party, such as Thawte and Verisign.