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 given hosting provider for your domain name is the easiest 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), and so on, so if you need to modify any one of these records, you'll be able to do it through their system. In other words, 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 name you want to access. This way the website that you'll see is going to be retrieved from the proper location. The name servers usually have a prefix “ns” or “dns” and every single domain name has at least 2 NS records. There isn't any sensible difference between the two prefixes, so what kind a web hosting provider is going to use depends only on their preference.