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 given hosting provider for your domain is the simplest way to forward 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 forth, if you would like to edit any one of these records, you are going to be able to do it through their system. To put it differently, the NS records of a domain address point out 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 Internet domain you are trying to access. In this way the web site that you will see will be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and each and every domain address has at least 2 NS records. There isn't any functional difference between the two prefixes, so which one a web hosting provider is going to use depends only on their preference.