The Name Servers of a domain name reveal the DNS servers that deal with its DNS records. The Internet protocol address of the web site (A record), the mail server that manages the emails for a domain name (MX records), any text record in free form (TXT record), forwarding (CNAME record) etc are taken from the DNS servers of the web hosting provider and for any domain address to be using them and to be pointed to their hosting platform, it needs to have their name servers, or NS records. If you would like to open a site, for instance, and you type the URL, the web 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 webhosting provider where the A record of the website is retrieved, allowing you to view the content from the right location. Commonly a domain address has two name servers that start with NS or DNS as a prefix and the difference between the two is simply visual.