The Name Servers of a domain show the DNS servers that handle its DNS records. The IP of the site (A record), the mail server that takes care of the emails for a domain address (MX records), any text record in free form (TXT record), forwarding (CNAME record) and so on are taken from the DNS servers of the web hosting company and for any domain address to be using them and to be forwarded to their hosting platform, it has to have their name servers, or NS records. If you would like to open an Internet site, for instance, and you type in the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain address and the request is then redirected to the DNS servers of the hosting provider where the A record of the site is retrieved, so you can view the content from the proper location. Ordinarily 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 simply visual.