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 host company for your domain 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), etc, if you would like to modify any of these records, you will be able to do it via their system. To put it differently, the NS records of a domain name 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 get the DNS records of the Internet domain you are trying to access. This way the web site that you're going to see is going to be retrieved from the proper location. The name servers typically have a prefix “ns” or “dns” and each domain address has at least two NS records. There is no sensible difference between the two prefixes, so which one a website hosting provider is going to use depends exclusively on their preference.