The NS, or Name Server records of a domain name, reveal which servers handle 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 handled on their end. This includes A (the IP address of the server/website), MX (mail server), TXT (free text), SRV (services), CNAME (forwarding), etcetera, so if you would like to change any one of these records, you're going to be able to do it via their system. In other words, 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 reach. In this way the web site you'll see is going to be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and every single domain name has at least 2 NS records. There is no sensible difference between the two prefixes, so what type a host company is going to use depends only on their preference.