The Name Servers of a domain name point out the DNS servers that handle its DNS records. The IP address of the web site (A record), the mail server that takes care of the e-mails for a domain name (MX records), any text record in free form (TXT record), directing (CNAME record) and so forth are taken from the DNS servers of the website hosting provider and for any domain name to be using them and to be forwarded to their hosting platform, it ought to have their name servers, or NS records. If you want to open a website, for instance, and you type in 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 site is retrieved, so that you can see 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 just visual.