Domain name - symbolic name, serving to identify areas - units of administrative autonomy on the Internet - as part of a higher hierarchy of such an area. Each of these areas is called domain. The common namespace of the Internet functions thanks to the DNS - the domain name system.. Domain names make it possible to address Internet nodes and network resources located on them (websites, email servers, other services) in a human-friendly form.

Full domain name consists of the immediate domain name and then the names of all domains, in which it is included, separated by dots. for instance, full name www.ach.org.ua denotes the fourth-level domain www, which is part of a third-level domain but, which is part of the second-level domain kiev (denotes a region) top level ua, which is part of the geographic root domain. In everyday speech, a domain name is often understood as a fully qualified domain name..

Domain zone - a set of domain names of a certain level, belonging to a specific domain. for instance, zone kiev.ua includes all third-level domain names in this domain. The term "domain zone" is mainly used in the technical field, when setting up DNS servers (zone maintenance, zone delegation, zone transfer).