The NS, or Name Server records of a domain, indicate which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain name is the most convenient way to point 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), and so on, so if you would like to edit any one of these records, you'll 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 try to open a web address, the DNS servers are contacted to get the DNS records of the domain name you want to access. In this way the website that you'll see is going to be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and each and every domain has at least 2 NS records. There isn't any functional difference between the two prefixes, so what kind a hosting provider will use depends completely on their preference.