The Name Servers of a domain name show the DNS servers that manage its DNS records. The IP of the web site (A record), the mail server that takes care of the emails 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 domain name to be using them and to be pointed to their hosting platform, it has to have their name servers, or NS records. If you would like to open a website, for instance, and you enter the URL, the web browser connects to a DNS server, which keeps the NS records for the domain name and the request is then pointed to the DNS servers of the hosting provider where the A record of the site is obtained, allowing you to view the content from the right location. Ordinarily a domain address has 2 name servers that start with NS or DNS as a prefix and the difference between the two is simply visual.