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 particular host company for your domain is the easiest way to direct it to their system and all its sub-records are going to be managed 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, if you wish to edit some of these records, you will be able to do it through their system. Put simply, the NS records of a domain point out 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 name you are trying to access. That way the web site you'll see will be retrieved from the right location. The name servers usually have a prefix “ns” or “dns” and each domain name has at least two NS records. There isn't any functional difference between the two prefixes, so which one a host company will use depends entirely on their preference.