The NS, or Name Server records of a domain name, reveal which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain is the most effective way to direct 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), etc, so, in case you need to edit any one of these records, you're going to be able to do it through their system. Put simply, the NS records of a domain name 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 obtain the DNS records of the Internet domain you are attempting to reach. In this way the site that you will see is going to be retrieved from the right location. The name servers typically have a prefix “ns” or “dns” and every single domain name has at least 2 NS records. There isn't any practical difference between the two prefixes, so what kind a web hosting provider is going to use depends exclusively on their preference.