The NS, or Name Server records of a domain, point out which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain name is the easiest way to forward 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), etc, so if you need to edit any one of these records, you're going to be able to do it using their system. In other words, the NS records of a domain address reveal the DNS servers which 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 domain name you are attempting to reach. This way the website that you're going to see will be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and every single domain has at least two NS records. There isn't any functional difference between the two prefixes, so what type a host company will use depends solely on their preference.