Domain Names are host names that the Domain Name System (DNS) uses to identify and map to websites and other Internet Protocol (IP) resources. A good parallel would be to think of domain names as street names. Street names are important because they help people navigate. The IP addresses, on the other hand, are the geographical location of the streets themselves

The Domain Name System (DNS) is a hierarchical naming system that helps users find their way around the Internet. Each resource connected the Internet, such as a computer, has a unique address - just like a telephone number - that is a complicated string of numbers called an "IP address" (IP stands for "Internet Protocol" ). Because IP Addresses are difficult to remember, the DNS makes using the Internet easier by appropriating a string of letters (the "domain name") to be used instead of complex IP address. So instead of typing 304.252.198.1, you can type www.domaintools.com. It is a "mnemonic" device that makes addresses easier to remember.

Domain names are organized via subdomains which are subordinate levels of the Domain Name System root domain. Top-level domains (TLDs) are the first-level set of domain names, and include generic top-level domains (gTLDs) such as .com, .net and .org as well as country code top-level domains (ccTLDs). The ccTLDs are noted to the right of the dot, such as .fr or .au in the examples google.fr and google.com.au. Under Top-level domains, there are second and third-level domain names in the DNS hierarchy, such as DomainTools or Google. These domains are typically available for end-users to reserve so they can run web sites, create publicly accessible Internet resources, and connect the Internet to local area networks. Second level domains typically provide the name of the organization and /ore are descriptive of the service provided, while third level domains is typically used to refer to a specific server within an organization.