The NS, or Name Server records of a domain, reveal which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a particular host company for your domain is the most effective way to direct 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), etc, so if you need to edit any of these records, you are going to be able to do it using their system. To put it differently, the NS records of a domain address reveal 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 want to access. This way the web site that you will see is going to be retrieved from the right location. The name servers typically have a prefix “ns” or “dns” and every single domain has at least two NS records. There is absolutely no sensible difference between the two prefixes, so what type a hosting provider will use depends completely on their preference.