The NS, or Name Server records of a domain, reveal which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a particular hosting provider for your domain address is the most effective way to direct 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), etc, so, in case you would like to edit any one of these records, you're going to be able to do it through their system. To put it differently, the NS records of a domain show the DNS servers that 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. That way the web site that you're going to see will be retrieved from the correct location. The name servers usually have a prefix “ns” or “dns” and each domain name has at least 2 NS records. There's no functional difference between the two prefixes, so which one a web hosting provider will use depends entirely on their preference.