The Name Servers of a domain point out the DNS servers that are responsible for its DNS records. The IP of the website (A record), the mail server that handles the e-mails for a domain name (MX records), any text record in free form (TXT record), directing (CNAME record) and so forth are obtained from the DNS servers of the website hosting provider and for any domain to be using them and to be pointed to their hosting platform, it has to have their name servers, or NS records. If you would like to open an Internet site, for example, and you input the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain and the request is then sent to the DNS servers of the hosting provider where the A record of the website is obtained, allowing you to see the content from the correct location. Usually a domain has two name servers that start with NS or DNS as a prefix and the contrast between the two is just visual.