The NS, or Name Server records of a domain name, show which servers manage 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 point 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), etcetera, so, in case you wish to modify any one of these records, you will be able to do it by using their system. Put simply, the NS records of a domain address point out the DNS servers that are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to retrieve the DNS records of the domain you are attempting to access. This way the site you'll see will be retrieved from the right location. The name servers usually have a prefix “ns” or “dns” and every single domain name has at least 2 NS records. There isn't any sensible difference between the two prefixes, so what kind a web hosting provider will use depends only on their preference.