The NS, or Name Server records of a domain, point out which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given hosting provider for your domain name is the most convenient way to forward it to their system and all its sub-records are going to be taken care of 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 using their system. To put it differently, the NS records of a domain address 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 you are trying to reach. This way the website that you will see is going to be retrieved from the proper location. The name servers typically have a prefix “ns” or “dns” and each domain address has at least 2 NS records. There's no functional difference between the two prefixes, so what type a web hosting provider is going to use depends completely on their preference.