Some certificates are not issued directly under a root certificate (sometimes also called root certificate), but under a so-called intermediate certificate, which then stands between the actual (so-called end point) certificate and the root certificate. It is even possible that there is not only one intermediate certificate but several intermediate certificates between the endpoint and root certificates.
There are many reasons for intermediate certification. Some certification bodies achieve lower prices for their certificates because they do not have to maintain an expensive master certification body. Other certification authorities increase the coverage of an endpoint certificate by so-called cross-signing, in which the endpoint certificate is signed by several root certificates located in a certification path, whereby one root certificate is then available in a certain browser (or already from a previous version in a certain browser), the other root certificate in another browser (or already from a previous version in another browser). If a browser now does not know one of the root certificates, there is a chance that it may know another root certificate and recognize the endpoint certificate as trustworthy.
Together with the intermediate certificates, there is a so-called certification path with the root certificate at the top end and the requested certificate at the bottom end. This path must be mapped by installing the intermediate certificates on the server once. The calling browsers then receive all necessary certificates from the server when calling up an inter-certified website, in order to be able to map and verify the complete path as well. Thus the certificate is recognized and supported by the named browsers without further confirmation and without manual installation of certificates on the user side.
You will receive instructions from us on how to install the software, which you can usually do yourself. In case of doubt, please contact your provider. It is possible that some appliances do not support the import of intermediate certificates, please check the instructions for your appliance to see if it supports intermediate certificates. In case of doubt, we will of course cancel the certificate for you and you can switch to a product that is not certified in between. Of course our free support is also available to you here with advice and action.