The NS, or Name Server records of a domain name, show which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a particular hosting provider for your domain is the most effective way to point it to their system and all its sub-records are going to be managed 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 wish to modify some of these records, you will be able to do it through their system. To put it differently, the NS records of a domain name point out the DNS servers that are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to retrieve the DNS records of the Internet domain you want to reach. That way the website you'll see is going to be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and every single domain address has at least two NS records. There isn't any functional difference between the two prefixes, so what kind a web hosting provider is going to use depends entirely on their preference.