The Name Servers of a domain show the DNS servers that deal with its DNS records. The Internet protocol address of the web site (A record), the mail server that manages the e-mails for a domain (MX records), any text record in free form (TXT record), forwarding (CNAME record) etc are taken from the DNS servers of the web hosting provider and for any domain name to be using them and to be pointed to their hosting platform, it has to have their name servers, or NS records. If you wish to open an Internet site, for instance, and you input the URL, the browser connects to a DNS server, which keeps the NS records for the domain address and the request is then pointed to the DNS servers of the hosting provider where the A record of the site is retrieved, so that you can see the content from the right location. Ordinarily a domain address has a couple of name servers that start with NS or DNS as a prefix and the difference between the two is only visual.