The NS, or Name Server records of a domain name, reveal which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a given hosting provider for your domain name is the simplest 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), etcetera, so, in case you wish to modify any one of these records, you'll be able to do it through their system. To put it differently, the NS records of a domain show the DNS servers that 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 Internet domain you are attempting to reach. This way the web site you'll see is going to be retrieved from the right location. The name servers usually have a prefix “ns” or “dns” and every single domain address has at least two NS records. There is no practical difference between the two prefixes, so what type a website hosting provider is going to use depends solely on their preference.