The Name Servers of a domain name point out the DNS servers that deal with its DNS records. The IP of the web site (A record), the mail server that handles the e-mails for a domain name (MX records), any text record in free form (TXT record), forwarding (CNAME record) and so on are obtained from the DNS servers of the web hosting provider and for any domain name to be using them and to be directed to their hosting platform, it needs to have their name servers, or NS records. If you wish to open a website, for instance, and you type in the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain name and the request is then redirected to the DNS servers of the hosting company where the A record of the site is retrieved, enabling you to look at the content from the proper location. Usually a domain has 2 name servers that start with NS or DNS as a prefix and the difference between the two is just visual.