The NS, or Name Server records of a domain, reveal which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a specific hosting provider for your domain address is the most effective way to point 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 on, so if you want to edit any one of these records, you will be able to do it by using their system. In other words, the NS records of a domain name reveal 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 you want to access. That way the site that you're going to see is going to be retrieved from the correct location. The name servers typically have a prefix “ns” or “dns” and each domain address has at least 2 NS records. There is no sensible difference between the two prefixes, so what kind a host company will use depends completely on their preference.