The NS, or Name Server records of a domain name, point out which servers handle 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 direct it to their system and all its sub-records are going to 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), etc, so if you would like to change any one 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 point out 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 domain you are trying to access. This way the website you will see will be retrieved from the correct location. The name servers typically have a prefix “ns” or “dns” and each and every domain has at least two NS records. There is absolutely no sensible difference between the two prefixes, so which one a hosting provider will use depends completely on their preference.