The NS, or Name Server records of a domain name, point out which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a specific hosting provider for your domain address is the most effective way to point 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), etc, so, in case you would like to change some of these records, you are going to be able to do it through their system. Put simply, the NS records of a domain reveal the DNS servers that 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 you want to access. This way the web site that you're going to see is going to be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and each domain address has at least 2 NS records. There isn't any sensible difference between the two prefixes, so which one a host company will use depends exclusively on their preference.