DNS is a specialized software service running on servers that stores mappings between hostnames and their corresponding IP addresses.

It is similar to the contact list or phonebook on a mobile phone. Internet users and applications use domain names, but computers only understand numeric IP addresses. DNS translates names into addresses so traffic can reach the correct destination.

DNS servers use specialized protocols to communicate with each other and resolve names. The system was designed to use UDP port 53 by default and can also use TCP port 53 for larger responses or zone transfers.

In simple terms, DNS helps the internet find the right server when a user types a domain name in a browser or application.