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 particular hosting provider for your domain address is the simplest way to direct it to their system and all its sub-records are going to be taken care of 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 on, so if you wish to edit any one of these records, you will be able to do it by using their system. To put it differently, 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 get the DNS records of the Internet domain you are trying to access. That way the site you'll see is going to be retrieved from the correct location. The name servers typically have a prefix “ns” or “dns” and every single domain name has at least 2 NS records. There's no sensible difference between the two prefixes, so which one a hosting provider is going to use depends only on their preference.