The Name Servers of a domain point out the DNS servers that handle its DNS records. The IP 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), directing (CNAME record) and so on are obtained from the DNS servers of the hosting company and for any Internet domain to be using them and to be forwarded to their hosting platform, it has to have their name servers, or NS records. If you wish to open a site, for example, and you type the URL, the Internet 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 webhosting provider where the A record of the web site is obtained, enabling you to see the content from the proper location. Commonly a domain address has a couple of name servers that start with NS or DNS as a prefix and the distinction between the two is just visual.