The Name Servers of a domain name show the DNS servers that manage its DNS records. The IP address of the website (A record), the mail server that handles the emails for a domain name (MX records), any text record in free form (TXT record), forwarding (CNAME record) etc are extracted from the DNS servers of the web hosting provider and for any domain name to be using them and to be pointed to their hosting platform, it should have their name servers, or NS records. If you want to open a site, for instance, and you input the URL, the web browser connects to a DNS server, which keeps the NS records for the domain and the request is then pointed to the DNS servers of the hosting provider where the A record of the site is obtained, enabling you to look at the content from the proper location. Normally a domain name has two name servers that start with NS or DNS as a prefix and the difference between the two is only visual.