The NS, or Name Server records of a domain name, indicate which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given 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), and so on, if you need to change some of these records, you're going to be able to do it using 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 get the DNS records of the domain name you want to access. In this way the web site that you'll see is going to be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and each domain name has at least two NS records. There is absolutely no functional difference between the two prefixes, so what kind a host company is going to use depends solely on their preference.