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 simplest way to direct it to their system and all its sub-records are going to 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), and so forth, so if you would like to change any of these records, you are going to be able to do it using their system. In other words, the NS records of a domain address show the DNS servers which are authoritative for it, so when you try to open a web address, the DNS servers are contacted to obtain the DNS records of the domain you are attempting to reach. That way the web site that you're going to see is going to be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and every single domain name has at least two NS records. There isn't any practical difference between the two prefixes, so what kind a host company will use depends solely on their preference.