The NS, or Name Server records of a domain name, point out which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain name is the most effective way to forward it to their system and all its sub-records will 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), etcetera, so if you wish to change any of these records, you're going to be able to do it via their system. To put it differently, the NS records of a domain show the DNS servers that are authoritative for it, so when you try to open a web address, the DNS servers are contacted to get the DNS records of the domain name you are trying to access. This way the website you will see is going to be retrieved from the proper location. The name servers usually have a prefix “ns” or “dns” and every single domain name has at least 2 NS records. There is absolutely no functional difference between the two prefixes, so what kind a website hosting provider will use depends exclusively on their preference.