The Name Servers of a domain point out the DNS servers that are responsible for its DNS records. The Internet protocol address of the site (A record), the mail server that manages the e-mails for a domain (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 needs to have their name servers, or NS records. If you wish to open a site, for example, and you enter the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain name and the request is then redirected to the DNS servers of the hosting company where the A record of the web site is retrieved, so that you can look at the content from the proper location. Commonly a domain has 2 name servers that start with NS or DNS as a prefix and the contrast between the two is just visual.