The domain is an area of hierarchical names space of the Internet which is served by a set of domain names service (DNS) and is on-line administered. The domain is identified by the domain name.

Domain name is an address of network connection which identifies the owner of the address.

Registration of domains - represents entering the information on the domain and its manager in the central database with the purpose of uniqueness maintenance of the domain use, and reception of the rights to administration of the domain by the administrator. Service on registration of the domain is considered the information rendered from the moment of entering in a database. Registration of the domain usually operates within one year, beginning from the moment of the domain registration.

The sense of the address consists in that with a guarantee to result any interested person in the certain place. For example, having the true post address of the person, you can go to it on a visit, not being afraid thus, that you will get to somebody another. Business and with Internet addresses similarly is.

Addresses in the Internet are based on domain name system (DNS), each address consists of several levels.

There are two basic ways of addressing: symbolical for use by people and numerical, based on IP-addresses and used by a computer.

Each of the tens million computers entering into the Internet has own unique domain address, often named domain name or host name. This address looks as some words, reductions or other chains of symbols without the blanks going successively and divided by points.

Components of the domain address refer to as segments. The latest (right) segment named by the domain of top level, defines an accessory of a computer to a network of this or that country and consists usually of two letters, for example: .uk - Great Britain, .ru - Russia, au - Austria.

In the USA other system - thematic is traditionally used. In this system the domain of top level consists of three letters and designates an accessory of the address owner to one of following classes: .com - commercial sites, .edu - the educational organizations, .org - the other organizations.

Generally speaking, the domain is not the same, which "a segment of the domain addresses". The domain (this word means in translation "area") is obliged to specify unequivocally a site on the Internet of some set of units about which speak, that they belong to this domain.

As well as "house" in the post address is simultaneously located in some street, in some city and in some country, the same computer belongs at once to several domains. Domains of the Internet as nested dolls, are put each other, and the more finely the domain, its designation consists of segments greater number.

Apparently from this example, following the domain of top level the segment (if to read from right to left) can specify city, staff and to that similar geographical divisions. For example, in USA the domain of the second level can designate (usually designates) city, or geographical region where this address is located.

However more often right after the domain of top level there is a segment designating the organization or firm to which possesses this unit of the Internet. For example: company.com a business concern "Company", stanford.edu Stanford university, the USA.

Domain addresses of computers about which we now spoke, are intended for people. When one unit tries to find another on the Internet, it uses other type of the address - the so-called IP-address (IP - Internet Protocol). If the domain address can be compared to a name of the person the IP-address is its "phone number" which only and gives a real opportunity to contact it.

The IP-address is similar to the domain address that also consists of the segments forming hierarchical system. However in difference from the domain address, number of these segments in the IP-address always equally to four, and segments represent not lines of symbols, and numbers in a range from 0 up to 255 (in decimal record). Besides in IP-addresses the scale of ranks goes down from left to right, instead of from right to left, as in domain addresses. It means, that two computers - the neighbor on the Internet will differ, most likely, with last segment of the IP-addresses and the first segment of domain addresses.

Example:
194.105.195.17
147.115.3.27
- represent two IP addresses.

For definition on domain address IP-addresses on special units of the Network are available Tables of conformity. Such units refer to as servers DNS (Domain Name Service). To a computer the address even one such server should be known. If this server will not know the IP-address of unit which is necessary to you, it to address to other servers of system DNS nearest to them, i.e. - to the neighbors, and so on. When the necessary IP-address, at last, will be found on one of servers DNS, it there and then will send on your computer.