The NS, or Name Server records of a domain, reveal which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a particular hosting provider for your domain is the easiest way to point 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), and so on, so if you would like to modify some of these records, you'll be able to do it by using their system. In other words, the NS records of a domain name reveal the DNS servers that are authoritative for it, so when you try to open a web address, the DNS servers are contacted to retrieve the DNS records of the domain name you are trying to access. In this way the site that you'll see is going to be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and each domain name has at least two NS records. There is absolutely no sensible difference between the two prefixes, so what type a web hosting provider will use depends completely on their preference.