The Name Servers of a domain reveal the DNS servers that manage its DNS records. The Internet protocol address of the website (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) etc are taken from the DNS servers of the web hosting provider and for any Internet domain to be using them and to be directed to their hosting platform, it should have their name servers, or NS records. If you wish to open a website, for example, and you type the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain name and the request is then sent to the DNS servers of the hosting company where the A record of the website is retrieved, allowing you to look at the content from the correct location. Normally a domain name has a couple of name servers that start with NS or DNS as a prefix and the distinction between the two is only visual.