The NS, or Name Server records of a domain, indicate which servers manage the Domain Name System (DNS) records for it. Setting the name servers of a specific host company for your domain name is the most effective way to forward it to their system and all its sub-records will 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), etcetera, so, in case you would like to change some of these records, you are going to be able to do it by using their system. To put it differently, the NS records of a domain address show 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 domain name you are attempting to access. That way the site that you're going to see will be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and each and every domain name has at least 2 NS records. There is no functional difference between the two prefixes, so what type a host company is going to use depends only on their preference.