Domain names are formed by the rules and procedures of the Domain Name System (DNS).

It associates various information with domain names assigned to each of the participating entities.

In general, a domain name represents an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a web site, or the web site itself or any other service communicated via the Internet. Host names appear as a component in Uniform Resource Locators (URLs) for Internet resources such as web sites (e.g., en.wikipedia.org).

A website is a collection of related web pages, including multimedia content, typically identified with a common domain name, and published on at least one web server.

The first-level set of domain names are the top-level domains (TLDs), including the generic top-level domains (gTLDs), such as the prominent domains com, info, net, edu, and org, and the country code top-level domains (ccTLDs).

A top-level domain (TLD) is one of the domains at the highest level in the hierarchical Domain Name System of the Internet.

The registration of these domain names is usually administered by domain name registrars who sell their services to the public.

A domain name registrar is an organization that manages the reservation of Internet domain names.

A fully qualified domain name (FQDN) is a domain name that is completely specified with all labels in the hierarchy of the DNS, having no parts omitted.

A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name, is a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS).

'sos' is said to be a sub-domain of 'state.oh.us', and 'state' a sub-domain of 'oh.us', etc. In general, subdomains are domains subordinate to their parent domain.

In the Domain Name System (DNS) hierarchy, a subdomain is a domain that is a part of a main domain.

A domain name is an identification string that defines a realm of administrative autonomy, authority or control within the Internet.

ICANN coordinates the assignment of unique identifiers for use on the Internet, including domain names, Internet Protocol (IP) addresses, application port numbers in the transport protocols, and many other parameters.

A domain name consists of one or more parts, technically called labels, that are conventionally concatenated, and delimited by dots, such as example.com.

example.com, example.net, example.org, and example.edu are second-level domain names reserved for documentation purposes and examples of the use of domain names.

Such examples are the realm identifiers used in the Session Initiation Protocol (SIP), the Domain Keys used to verify DNS domains in e-mail systems, and in many other Uniform Resource Identifiers (URIs).

Such examples are the realm identifiers used in the Session Initiation Protocol (SIP), the Domain Keys used to verify DNS domains in e-mail systems, and in many other Uniform Resource Identifiers (URIs).

For example, the URL refers to a resource identified as whose representation, in the form of HTML and related code, is obtainable via the Hypertext Transfer Protocol (http:) from a network host whose domain name is.

ICANN approved the Internationalized domain name (IDNA) system, which maps Unicode strings used in application user interfaces into the valid DNS character set by an encoding called Punycode.

An internationalized domain name (IDN) is an Internet domain name that contains at least one label that is displayed in software applications, in whole or in part, in a language-specific script or alphabet, such as Arabic, Chinese, Cyrillic, Tamil, Hebrew or the Latin alphabet-based characters with diacritics or ligatures, such as French.

Therefore, ftp.example.com might be an FTP server, www.example.com would be a World Wide Web server, and mail.example.com could be an email server, each intended to perform only the implied function.

Multiple web pages with a common theme, a common domain name, or both, make up a website.

The registry receives registration information from each domain name registrar authorized to assign names in the corresponding TLD and publishes the information using a special service, the WHOIS protocol.

WHOIS (pronounced as the phrase "who is") is a query and response protocol that is widely used for querying databases that store the registered users or assignees of an Internet resource, such as a domain name, an IP address block or an autonomous system, but is also used for a wider range of other information.

Intercapping is often used to emphasize the meaning of a domain name.

It is also sometimes used in online usernames such as "johnSmith", and to make multi-word domain names more legible, for example in advertisements.

Such examples are the realm identifiers used in the Session Initiation Protocol (SIP), the Domain Keys used to verify DNS domains in e-mail systems, and in many other Uniform Resource Identifiers (URIs).

DomainKeys (informally DK) is a deprecated e-mail authentication system designed by Yahoo to verify the domain name of an e-mail sender and the message integrity.

In the latter form, a hostname is also called a domain name.

The Internet Assigned Numbers Authority (IANA) maintains an annotated list of top-level domains in the DNS root zone database.

In the case of the two major Internet namespaces, namely IP addresses and domain names, extra administrative policy and delegation to subordinate administrations is required because of the multi-layered distributed use of these resources.

The Truth in Domain Names Act follows the more general Anticybersquatting Consumer Protection Act passed in 1999 aimed at preventing typosquatting and deceptive use of names and trademarks in domain names.

The Anticybersquatting Consumer Protection Act (ACPA), 15 U.S.C. § 1125(d), is a U.S. law enacted in 1999 that established a cause of action for registering, trafficking in, or using a domain name confusingly similar to, or dilutive of, a trademark or personal name.

The most important function of DNS servers is the translation (resolution) of human-memorable domain names and hostnames into the corresponding numeric Internet Protocol (IP) addresses, the second principal name space of the Internet which is used to identify and locate computer systems and resources on the Internet.

Host names appear as a component in Uniform Resource Locators (URLs) for Internet resources such as web sites (e.g., en.wikipedia.org).

The format combines the pre-existing system of domain names (created in 1985) with file path syntax, where slashes are used to separate directory and filenames.

A domain hack is a domain name that suggests a word, phrase, or name when concatenating two or more adjacent levels of that domain.

Domain names used in works of fiction have often been registered in the DNS, either by their creators or by cybersquatters attempting to profit from it. This phenomenon prompted NBC to purchase the domain name Hornymanatee.com after talk-show host Conan O'Brien spoke the name while ad-libbing on his show.

Cybersquatting (also known as domain squatting), according to the United States federal law known as the Anticybersquatting Consumer Protection Act, is registering, trafficking in, or using an Internet domain name with bad faith intent to profit from the goodwill of a trademark belonging to someone else.

load balancing) or even identical addresses (cf.

In this technique, multiple IP addresses are associated with a single domain name; clients are given IP in round robin fashion.

Domain name speculation is the practice of identifying and registering or acquiring Internet domain names as an investment with the intent of selling them later for a profit.

Domain hijacking or domain theft is the act of changing the registration of a domain name without the permission of its original registrant, or by abuse of privileges on domain hosting and registrar(s) software systems.