The Name Servers of a domain point out the DNS servers that handle its DNS records. The Internet protocol address of the website (A record), the mail server that handles the emails for a domain (MX records), any text record in free form (TXT record), pointing (CNAME record) and so forth are obtained from the DNS servers of the website hosting company and for any domain address to be using them and to be forwarded to their hosting platform, it needs to have their name servers, or NS records. If you would like to open an Internet site, for instance, and you type the URL, the web browser connects to a DNS server, which keeps the NS records for the domain address and the request is then forwarded to the DNS servers of the hosting provider where the A record of the site is obtained, so that you can look at the content from the correct location. Normally a domain has 2 name servers that start with NS or DNS as a prefix and the difference between the two is only visual.