The Name Servers of a domain point out the DNS servers that handle its DNS records. The IP of the web site (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), directing (CNAME record) and so on are taken from the DNS servers of the website hosting company and for any Internet domain to be using them and to be directed to their hosting platform, it should have their name servers, or NS records. If you want to open a website, for example, and you type in the URL, the 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 webhosting provider where the A record of the site is retrieved, so that you can look at the content from the right location. Usually a domain address has a couple of name servers that start with NS or DNS as a prefix and the distinction between the two is only visual.
