The NS, or Name Server records of a domain name, point out which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a particular host company for your domain address is the most convenient way to direct it to their system and all its sub-records will 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), etc, so if you need to edit any one of these records, you are going to be able to do it by using their system. In other words, the NS records of a domain 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 reach. In this way the website that you're going to see is going to be retrieved from the proper location. The name servers usually have a prefix “ns” or “dns” and each domain has at least two NS records. There's no sensible difference between the two prefixes, so what kind a web hosting provider will use depends solely on their preference.