The Name Servers of a domain name show the DNS servers that are responsible for its DNS records. The Internet protocol address of the site (A record), the mail server that deals with the emails for a domain (MX records), any text record in free form (TXT record), directing (CNAME record) and so forth are extracted from the DNS servers of the hosting provider and for any domain address to be using them and to be pointed to their hosting platform, it has to have their name servers, or NS records. If you want to open a website, for example, and you type in the URL, the web browser connects to a DNS server, which keeps the NS records for the domain address and the request is then sent to the DNS servers of the webhosting provider where the A record of the website is retrieved, allowing you to see the content from the right location. Usually a domain name has a couple of name servers that start with NS or DNS as a prefix and the contrast between the two is simply visual.