The domain name system or domain name server (DNS) is a system that stores and associates many types of information with domain names, but, most important, it translates the domain name (computer hostnames) to IP addresses. It also lists mail exchange servers accepting e-mail for each domain. In providing a worldwide keyword-based redirection service, DNS is an essential component of contemporary Internet use.

Useful for several reasons, the DNS is most well-known for making it possible to attach easy-to-remember domain names (such as “rrwdg.com”) to hard-to-remember IP addresses (such as 207.142.131.206). Humans take advantage of this when they recite URLs and e-mail addresses. Less recognized, the domain name system makes it possible for people to assign authoritative names, without needing to communicate with a central registrar each time.

=> .aero - for the air transport industry
=> .biz - for business use
=> .cat - for Catalan language/culture
=> .com - for commercial organizations, but unrestricted
=> .coop - for cooperatives
=> .edu - for post-secondary educational establishments
=> .gov - for governments and their agencies in the United States
=> .info - for informational sites, but unrestricted
=> .int - for international organizations established by treaty
=> .jobs - for employment-related sites
=> .mil - for the US military
=> .mobi - for sites catering to mobile devices
=> .museum - for museums
=> .name - for families and individuals
=> .net - originally for network infrastructures, now unrestricted
=> .org - originally for organizations
=> .pro - for certain professions
=> .travel - for travel agents, airlines, hoteliers, tourism bureaus, etc.