The NS, or Name Server records of a domain name, point out which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a given host company for your domain name is the simplest 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 if you want to change some of these records, you're going to be able to do it using their system. Put simply, the NS records of a domain name 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 domain you are trying to reach. In this way the site that you'll see will be retrieved from the correct location. The name servers normally have a prefix “ns” or “dns” and every single domain has at least two NS records. There isn't any practical difference between the two prefixes, so what type a web hosting provider is going to use depends exclusively on their preference.