Root certificate identifies the Root Certification Authority. Certification Authority issues multiple certificates in the form of a tree structure. A root certificate is the top-most certificate of the tree. All certificates below the root certificate inherit its trustworthiness (a signature by a root certificate is similar to ‘notarizing’ an identity in the physical world). A certificate signed by a Root CA is implicitly trusted by most web browsers. Intermediate certificate is the secondary certificate of CA's tree structure.

Root and intermediate (if available) certificates have to be installed on web server of the hosting server where your domain is hosted for your SSL certificate to work properly. 

Root and intermediate certificates are included in the certificate files you can download from your account panel. If you need assistance don't hesitate to contact our Support Team.