Name Servers, or sometimes used as nameservers is a web hosting term for a human language of IP addresses pointing at a domain or a particular host. Typically, you will have 2 name servers so if one fails, the other will point that domain to the correct location. The process of performing the pointing of the domain is through a server known as the DNS server (Domain Name System). After a visitor passes through the DNS, they will reach the target server, and then may be directed to other locations on the target server as well. Name server settings are generally stored within all web hosting domain provider accounts. Name servers usually takes time to change or propagate depending on the TTL (Time To Live) settings on the web hosting provider.
For more information, please see:
http://en.wikipedia.org/wiki/Name_server
