The Name Servers of a domain name point out the DNS servers that handle its DNS records. The IP address of the website (A record), the mail server that handles the emails for a domain address (MX records), any text record in free form (TXT record), forwarding (CNAME record) etc are extracted from the DNS servers of the web hosting company and for any Internet domain to be using them and to be pointed to their hosting platform, it should have their name servers, or NS records. If you would like to open a website, for instance, and you enter the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain address and the request is then sent to the DNS servers of the webhosting provider where the A record of the site is obtained, so you can see the content from the right location. Ordinarily a domain has 2 name servers that start with NS or DNS as a prefix and the distinction between the two is just visual.