The Name Servers of a domain show the DNS servers that handle its DNS records. The IP of the site (A record), the mail server that manages the e-mails for a domain address (MX records), any text record in free form (TXT record), pointing (CNAME record) and so forth are extracted from the DNS servers of the hosting provider and for any domain address to be using them and to be forwarded to their hosting platform, it should have their name servers, or NS records. If you want to open an Internet site, for instance, and you type the URL, the web browser connects to a DNS server, which keeps the NS records for the domain and the request is then sent to the DNS servers of the webhosting provider where the A record of the site is obtained, so you can look at the content from the proper location. Ordinarily a domain address has 2 name servers that start with NS or DNS as a prefix and the distinction between the two is only visual.