The NS, or Name Server records of a domain, reveal 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 simplest way to forward 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 if you want to modify any one of these records, you're going to be able to do it through their system. In other words, the NS records of a domain show the DNS servers that 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 trying to access. That way the site that you will see will be retrieved from the proper location. The name servers usually have a prefix “ns” or “dns” and every single domain name has at least two NS records. There is absolutely no practical difference between the two prefixes, so what type a hosting provider will use depends entirely on their preference.