The NS, or Name Server records of a domain name, point out which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given hosting provider for your domain is the simplest way to forward it to their system and all its sub-records will 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 want to modify any of these records, you're going to be able to do it using their system. In other words, the NS records of a domain name reveal the DNS servers which 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 name you are attempting to reach. That way the website you'll see will be retrieved from the correct location. The name servers usually have a prefix “ns” or “dns” and every single domain address has at least two NS records. There isn't any functional difference between the two prefixes, so what kind a website hosting provider will use depends entirely on their preference.