The Name Servers of a domain show the DNS servers that deal with its DNS records. The IP address of the website (A record), the mail server that takes care of the e-mails for a domain address (MX records), any text record in free form (TXT record), pointing (CNAME record) etc are obtained from the DNS servers of the hosting company and for any domain to be using them and to be forwarded to their hosting platform, it has to have their name servers, or NS records. If you want to open an Internet site, for instance, and you type the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain address and the request is then pointed to the DNS servers of the webhosting provider where the A record of the site is retrieved, allowing you to look at the content from the right location. Usually a domain name has two name servers that start with NS or DNS as a prefix and the contrast between the two is only visual.