A certificate is a statement guaranteeing the identity of a person or the security of a Web site. Internet Explorer uses two different types of certificates.
A "personal certificate" is a kind of guarantee that you are who you say you are. You specify information about yourself, such as your username and password. This information is used when you send personal information over the Internet to a Web site that requires a certificate verifying your identity.
A "Web site certificate" states that a specific Web site is secure and genuine. It ensures that no other Web site can assume the identity of the original secure site. Web site certificates are also dated when they are issued. When you try to open an organization�s Web site, Internet Explorer verifies that the Internet address stored in the certificate is correct and that the current date precedes the expiration date. If the information is not current and valid, Internet Explorer can display a warning.