The Common Name (also CN) identifies the host name associated with the certificate, for example www.example.com or example.com.
It consists of a single host name in case of a single-name certificate (e.g. example.com, www.example.com), or a wildcard name in case of a wildcard certificate (e.g. *.example.com). In all cases, it is not an URL and therefore it doesn’t include any protocol (e.g. http:// or https://), port number, or pathname.