The Domain Name System protocol (DNS) is a query protocol whereby if the server is given a Domain Name, it will respond with the associated IP address. To use the system, a DNS server address must be added to your computers newtork configuration table. This can be done either by hard-coding the address into the table yourself, or if the service is available, by letting the ISP dynamically provide an address. Secondary addresses can usually also be added to the table as a fallback, should the primary address server fail.
As Domain Names must be unique, an organization called the Internet Assigned Numbers Authority (IANA) has established itself to regulate the naming. Their authorized selling of name rights has become a huge income business, with horror stories about squatting abuses and about how Domain Names are snatched from legitimate leasees and given to large corporations. There is no reason however why another agency could not regulate the issuance of Domain Names that do not conflict with IANA names, and which circumvent IANAs fee-charging monopoly. One such alternative naming authority, which offers FREE TLDs, is called "OpenNIC". The OpenNIC community offers a mailing list for technical and non-technical discussions about OpenNIC.
Unfortunately the IANA registrars and their top tier DNS servers refuse to regognize OpenNIC Domain Names (and these IANA servers are where most ISP DNS servers look to populate their own lookup tables), so to reach these addresses you must use a public OpenNIC server (note that these OpenNic servers will also recognize all of the normal IANA DNS names). Don't set your computer to "Obtain DNS server address automatically", but instead set the computer to "Use the following DNS server addresses" (which you will provide). Below are addresses for public DNS servers, both OpenNic and IANA.