The NS, or Name Server records of a domain, indicate 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 simplest way to forward it to their system and all its sub-records will be handled 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, in case you wish to change any one of these records, you are going to be able to do it by using their system. To put it differently, the NS records of a domain address point out 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. This way the site you'll see is going to be retrieved from the right location. The name servers typically have a prefix “ns” or “dns” and each domain has at least two NS records. There is no practical difference between the two prefixes, so what type a web hosting provider will use depends exclusively on their preference.