DNS (Domain Name System) is the largest database of information about every website on the internet. Domain Name System translates domain names into IP addresses. Domain names are easier to remember, but the internet is based on IP addresses. Every website has an IP address that is its internet location.
The purpose of DNS
To use easy-to-remember domain names for websites instead of their numeric IP addresses. For example the domain name www.email-freeplan.com might be translated to 184.108.40.206. The data that tells the web server how to respond to your input is known as the DNS records, or zone files. These records play a significant role in the functionality of the internet.
DNS syntax is a set of commands that dictate the actions of the DNS server. The most used records stored in the DNS database are IP addresses like A and AAAA; domain name aliases like CNAME; SMTP mail exchangers like MX; pointers for reverse DNS lookups like PTR; and name servers like NS or Start of Authority (SOA).
You can find more information about DNS here.