The NS, or Name Server records of a domain name, show which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain name is the most convenient 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), and so on, so, in case you need to change any one of these records, you're going to be able to do it using their system. In other words, the NS records of a domain address reveal the DNS servers that are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to obtain the DNS records of the domain you are trying to reach. That way the site that you're going to see will be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and each and every domain name has at least 2 NS records. There isn't any sensible difference between the two prefixes, so what type a web hosting provider is going to use depends completely on their preference.