The NS, or Name Server records of a domain name, point out which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a specific hosting provider for your domain address is the most convenient way to forward it to their system and all its sub-records are going to 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, if you wish to modify any one of these records, you're going to be able to do it by using their system. To put it differently, the NS records of a domain point out the DNS servers which are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to obtain the DNS records of the domain you are trying to reach. This way the website that you're going to see will be retrieved from the correct location. The name servers typically have a prefix “ns” or “dns” and every single domain address has at least two NS records. There isn't any sensible difference between the two prefixes, so which one a web hosting provider will use depends completely on their preference.