The Name Servers of a domain reveal the DNS servers that manage its DNS records. The IP of the website (A record), the mail server that handles the emails for a domain address (MX records), any text record in free form (TXT record), directing (CNAME record) and so forth are obtained from the DNS servers of the web hosting company and for any domain to be using them and to be pointed to their hosting platform, it should have their name servers, or NS records. If you wish to open an Internet site, for example, and you insert the URL, the browser connects to a DNS server, which keeps the NS records for the domain name and the request is then sent to the DNS servers of the webhosting provider where the A record of the website is obtained, so you can see the content from the correct location. Usually a domain address has two name servers that start with NS or DNS as a prefix and the distinction between the two is just visual.