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 (MX records), any text record in free form (TXT record), pointing (CNAME record) and so forth are taken from the DNS servers of the web hosting company and for any domain name to be using them and to be directed to their hosting platform, it should have their name servers, or NS records. If you would like to open an Internet site, for example, and you input the URL, the web browser connects to a DNS server, which keeps the NS records for the domain name 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 see the content from the right location. Usually a domain address has 2 name servers that start with NS or DNS as a prefix and the difference between the two is simply visual.