The Name Servers of a domain name show the DNS servers that are responsible for its DNS records. The Internet protocol address of the site (A record), the mail server that handles the e-mails for a domain address (MX records), any text record in free form (TXT record), directing (CNAME record) etc are taken from the DNS servers of the web hosting provider and for any domain name to be using them and to be directed to their hosting platform, it should have their name servers, or NS records. If you would like to open a site, for example, and you type the URL, the browser connects to a DNS server, which keeps the NS records for the domain 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 look at the content from the correct location. Normally a domain has two name servers that start with NS or DNS as a prefix and the contrast between the two is simply visual.