The NS, or Name Server records of a domain name, show which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a specific host company for your domain is the most convenient way to direct 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, so if you wish to change any of these records, you are going to be able to do it by using their system. Put simply, the NS records of a domain name 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 get the DNS records of the domain name you are trying to access. That way the web site that you're going to see is going to be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and each domain address has at least two NS records. There's no functional difference between the two prefixes, so what kind a website hosting provider is going to use depends completely on their preference.