domain name system has a hierarchical structure:
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
"newest" generic Top Level Domains are .INFO and .BIZ.
Other TLDs will be added soon.
level domain is the component chosen by you, on the left of
the Top Level Domain. So Tuonome.it is a Second Level Domain.
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 email@example.com, FTP-service