The NS, or Name Server records of a domain, show 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 simplest way to direct it to their system and all its sub-records will 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), etcetera, so, in case you would like to edit any one of these records, you will be able to do it via their system. To put it differently, the NS records of a domain name 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 name you want to reach. That way the web site you'll see will be retrieved from the right location. The name servers normally have a prefix “ns” or “dns” and each domain has at least two NS records. There is no sensible difference between the two prefixes, so which one a web hosting provider is going to use depends completely on their preference.