The NS, or Name Server records of a domain, reveal which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a specific hosting provider for your domain address is the simplest way to forward it to their system and all its sub-records are going to 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 forth, so, in case you need to modify any of these records, you're going to be able to do it using their system. Put simply, the NS records of a domain address 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 retrieve the DNS records of the domain you want to reach. That way the web site that you'll see will be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and every single domain address has at least two NS records. There is absolutely no sensible difference between the two prefixes, so what type a website hosting provider is going to use depends exclusively on their preference.