The component furthest right to the domain name is called the Top Level Domain. Top Level Domains are often country code, for example .it (Italy), .be (Belgium), .nl (The Netherlands), .... However there are also generic Top Level Domanis, for example .COM, .NET and .ORG

The two "newest" generic Top Level Domains are .INFO and .BIZ. Other TLDs will be added soon.

The second level domain is the component chosen by you, on the left of the Top Level Domain. So Tuonome.it is a Second Level Domain.

To these SLD's a domain name holder can associate, by means of a number of technical procedures, all the Internet services: WEB  www.tuonome.it, e-mail helpdesk@tuonome.it, FTP-service and other.