The NS, or Name Server records of a domain name, indicate which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a particular hosting provider for your domain address is the most effective way to direct it to their system and all its sub-records will be handled on their end. This includes A (the IP address of the server/website), MX (mail server), TXT (free text), SRV (services), CNAME (forwarding), etc, so, in case you need to modify some of these records, you will be able to do it via their system. In other words, the NS records of a domain point out the DNS servers which are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to get the DNS records of the domain name you are trying to access. That way the site you will see is going to be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and each domain has at least two NS records. There isn't any sensible difference between the two prefixes, so what kind a website hosting provider will use depends completely on their preference.