CER files are security files that have been provided by a third party Certificate Authority, such as VeriSign or Thwate. CER files are used to verify the authenticity of a website. The CER file is installed on a Web server to establish the validity of a certain website hosted on the server. CER files can be viewed by clicking the lock icon near the edge of a browser window when accessing a secure site (secure sites use SSL encryption as seen by the "https://" prefix in the URL), to view the certificate in Safari, click the lock icon located near the top-right corner of the browser window.
Please rate how useful you found the information on this page: