The NS, or Name Server records of a domain, indicate which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a specific host company for your domain name is the most convenient way to direct 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), and so forth, so, in case you want to change some of these records, you are going to be able to do it via 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 obtain the DNS records of the domain you are attempting to access. This way the website you will see is going to be retrieved from the proper location. The name servers normally have a prefix “ns” or “dns” and every single domain has at least two NS records. There's no practical difference between the two prefixes, so what kind a website hosting provider will use depends solely on their preference.