The NS, or Name Server records of a domain, point out which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a particular host company for your domain address is the easiest way to forward it to their system and all its sub-records will 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), and so on, if you would like to modify any one of these records, you're going to be able to do it via 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 obtain the DNS records of the domain you want to reach. This way the website that you will see will be retrieved from the correct location. The name servers typically have a prefix “ns” or “dns” and each and every domain name has at least 2 NS records. There isn't any sensible difference between the two prefixes, so which one a web hosting provider is going to use depends completely on their preference.