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 particular hosting provider for your domain name is the simplest way to forward 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), etcetera, so, in case you want to modify some of these records, you're going to be able to do it through their system. Put simply, 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 retrieve the DNS records of the domain name you want to access. That way the website you'll see will be retrieved from the correct location. The name servers normally 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 what type a web hosting provider is going to use depends only on their preference.