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 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 forth, so, in case you need to edit any one of these records, you are going to be able to do it using their system. Put simply, the NS records of a domain 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 retrieve the DNS records of the domain name you are attempting to reach. In this way the web site that you'll see is going to be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and each and every domain address has at least two NS records. There is no sensible difference between the two prefixes, so what kind a host company will use depends solely on their preference.