The NS, or Name Server records of a domain name, indicate which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain address is the easiest way to direct it to their system and all its sub-records are going to 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), and so forth, so if you wish to edit any of these records, you'll be able to do it through their system. To put it differently, the NS records of a domain name reveal the DNS servers which are authoritative for it, so when you try to open a web address, the DNS servers are contacted to get the DNS records of the domain you are trying to reach. This way the site that you're going to see will be retrieved from the proper location. The name servers usually have a prefix “ns” or “dns” and each and every domain name has at least two NS records. There's no functional difference between the two prefixes, so what kind a web hosting provider is going to use depends only on their preference.