The NS, or Name Server records of a domain, indicate which servers deal with the Domain Name System (DNS) records for it. Setting the name servers of a particular host company for your domain name is the easiest way to point 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, so, in case you need to edit some of these records, you're going to be able to do it via their system. In other words, the NS records of a domain show the DNS servers that are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to obtain the DNS records of the Internet domain you are attempting to reach. That way the site that you will see will be retrieved from the right location. The name servers usually have a prefix “ns” or “dns” and each domain address has at least two NS records. There's no sensible difference between the two prefixes, so what type a website hosting provider will use depends entirely on their preference.