The NS, or Name Server records of a domain, indicate which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a particular host company for your domain is the easiest way to direct it to their system and all its sub-records will 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), etc, so, in case you wish to modify any of these records, you will be able to do it using their system. To put it differently, the NS records of a domain name point out 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 access. This way the website you will see is going to be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and each and every domain has at least 2 NS records. There's no sensible difference between the two prefixes, so what type a host company will use depends only on their preference.