When defining domain names there is a hierarchy (represented by levels) that allows you to add subdomains to the main domain name. A main domain name is a second-level domain name (the first one is the extension) in the format domainname.extension; examples of second-level domains are: hostingsolutions.it or google.com or even wikipedia.org.
A third-level domain (or subdomain) is a domain name in the  format subdomain.domainname.extension ; so, if the main domain name was mydomain.it, a third-level domain could be the word name added to the rest of the domain name, becoming name.mydomain.it. To name a famous domain, an example is it.wikipedia.org, where it corresponds to the third-level that is added to the second, wikipedia.org.

To add a third-level to a domain name, you must be the owner of the domain name (second level) and, in the case of Hosting Solutions, this is a free operation that can be activated from the control panel.

This function of the control panel allows you to create third levels of your domain (subdomain.domain.extension), for example administration.my domain.it, and redirect them to any web space.

The subdomain can be linked to pages hosted on a hosting plan already active with Hosting Solutions (for example, administration.mydomain.it can be linked to the content on www.mydomain.it/administration/), but also to addresses outside of Hosting Solutions.

To add a third level subdomain from the ServerMate control panel, please refer to the guide how to add third-level subdomains.