The Domain Name System (DNS) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network. The purpose of DNS is to translate human-readable domain names, such as "www.example.com," into machine-readable IP addresses, such as "192.0.2.1". DNS servers act like a phonebook for the internet, allowing people to input normal words into their browsers without having to keep track of the IP address for every website.

DNS servers translate requests for specific domains into IP addresses, controlling which server users with access when they enter the domain name into their browser. DNS caching is used to reduce the time it takes to get an answer to a DNS query, and DNS data can be cached in a number of places, including recursive resolvers.

In summary, the purpose of DNS is to translate domain names into IP addresses, allowing devices to be located and connected worldwide. DNS servers act like a phonebook for the internet, and DNS caching is used to reduce the time it takes to get an answer to a DNS query.