The NS, or Name Server records of a domain, indicate which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a specific hosting provider for your domain is the most effective way to point it to their system and all its sub-records are going to be managed 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 if you wish to modify any of these records, you are going to be able to do it via their system. In other words, the NS records of a domain show the DNS servers which are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to get the DNS records of the Internet domain you are attempting to access. In this way the website that you're going to see will be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and each and every domain name has at least two NS records. There is no functional difference between the two prefixes, so what kind a hosting provider is going to use depends completely on their preference.