The Name Servers of a domain name point out the DNS servers that handle its DNS records. The Internet protocol address of the web site (A record), the mail server that handles the emails for a domain (MX records), any text record in free form (TXT record), forwarding (CNAME record) etc are extracted from the DNS servers of the hosting provider and for any Internet domain 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 a site, for instance, and you type in the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain and the request is then forwarded to the DNS servers of the hosting provider where the A record of the web site is obtained, so that you can look at the content from the right location. Commonly a domain address has 2 name servers that start with NS or DNS as a prefix and the contrast between the two is simply visual.