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 host company for your domain is the most convenient way to point 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, in case you wish to modify 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 try to open a web address, the DNS servers are contacted to obtain the DNS records of the Internet domain you are trying to reach. In this way the site you'll see will be retrieved from the right location. The name servers typically have a prefix “ns” or “dns” and each domain name has at least two NS records. There isn't any practical difference between the two prefixes, so what type a hosting provider will use depends exclusively on their preference.