Extended Validation Certificates are the highest class of SSL available today and lend the most credibility to your website by prominently displaying your verified organization name directly in the browser interface.
Intermediate Certificates help complete a "Chain of Trust" from your SSL or Client Certificate to GlobalSign's Root Certificate.
As an ExtendedSSL customer you must install your end entity SSL Certificate (received via e-mail) along with an ExtendedSSL Intermediate Certificate listed below.
Instructions for installing SSL Certificates on various platforms can be found here:
Note: In some cases, the web server may need to be configured with the GlobalSign R3-R5 Cross Certificate or possibly with Root R3 or Root R5 as part of the standard configuration process.