The NS, or Name Server records of a domain, indicate which servers manage 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 point it to their system and all its sub-records will be managed on their end. This includes A (the IP address of the server/website), MX (mail server), TXT (free text), SRV (services), CNAME (forwarding), etc, if you need to modify any of these records, you are going to be able to do it through their system. To put it differently, the NS records of a domain reveal the DNS servers which are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to get the DNS records of the Internet domain you want to access. In this way the site you'll see will be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and each and every domain has at least 2 NS records. There is absolutely no sensible difference between the two prefixes, so which one a host company will use depends entirely on their preference.