Domain name system (DNS) is the system that is used to translate human-memorable domain names like namecheap.com and hostnames like support.namecheap.com into the corresponding numeric Internet Protocol (IP) addresses as well as to identify and locate computer systems and resources on the Internet.
When you use an alphanumeric address like "cloudcapsule.cc" your computer needs to understand what numerical IP address it should contact to show up the content. Domain name server is a server responsible for keeping the file that contains information about the domain name(s) and corresponding IP addresses (zone file) as well as for providing the above-mentioned information during DNS queries.
Domain name servers are a fundamental part of the Domain Name System. Nameserver is a server on the Internet specialized in handling queries regarding the location of the domain name’s various services. In easy words, name servers define your domain’s current DNS provider.
All domains usually have at least two DNS servers.
When you make a request for anything related to the domain name, it gets sent to one of the name servers. In response, the DNS server sends back the IP address. This works for the Web Site, Mail Servers, and anything else based on the domain name.