The NS, or Name Server records of a domain, point out which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a particular hosting provider for your domain is the most convenient way to direct it to their system and all its sub-records are going to be handled 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 want to edit any one of these records, you will be able to do it through 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 Internet domain you are attempting to access. This way the website that you're going to see will be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and every single domain has at least 2 NS records. There is absolutely no sensible difference between the two prefixes, so what type a website hosting provider will use depends completely on their preference.