The NS, or Name Server records of a domain, reveal which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain is the easiest 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), and so on, so if you would like to change any one of these records, you're going to be able to do it using their system. To put it differently, the NS records of a domain address reveal the DNS servers which are authoritative for it, so when you try to open a web address, the DNS servers are contacted to obtain the DNS records of the Internet domain you are trying to reach. That way the site you'll see will be retrieved from the correct location. The name servers typically have a prefix “ns” or “dns” and each and every domain has at least 2 NS records. There is no functional difference between the two prefixes, so what kind a hosting provider is going to use depends only on their preference.