The Name Servers of a domain show the DNS servers that manage its DNS records. The IP of the web site (A record), the mail server that deals with the emails for a domain (MX records), any text record in free form (TXT record), pointing (CNAME record) etc are extracted from the DNS servers of the web hosting company and for any domain name to be using them and to be pointed to their hosting platform, it should have their name servers, or NS records. If you wish to open an Internet site, for instance, and you type the URL, the web browser connects to a DNS server, which keeps the NS records for the domain and the request is then redirected to the DNS servers of the hosting provider where the A record of the site is retrieved, allowing you to look at the content from the right location. Usually a domain address has two name servers that start with NS or DNS as a prefix and the distinction between the two is simply visual.