The NS, or Name Server records of a domain, 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 point it to their system and all its sub-records will 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, if you would like to modify 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 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 obtain the DNS records of the domain name you want to access. In this way the site you will see will be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and each domain has at least two NS records. There isn't any practical difference between the two prefixes, so what kind a website hosting provider will use depends completely on their preference.