The Name Servers of a domain name point out the DNS servers that deal with its DNS records. The IP address of the web site (A record), the mail server that takes care of the e-mails for a domain (MX records), any text record in free form (TXT record), forwarding (CNAME record) and so on are taken from the DNS servers of the website hosting provider and for any Internet domain to be using them and to be directed to their hosting platform, it has to have their name servers, or NS records. If you would like to open a site, for instance, and you type in the URL, the 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 company where the A record of the web site is obtained, so you can view the content from the proper location. Commonly a domain address has 2 name servers that start with NS or DNS as a prefix and the distinction between the two is just visual.