The Domain Name System (DNS) is a hierarchical and decentralized naming system used to translate human-readable domain names (like www.example.com) into machine-readable IP addresses (such as 192.168.0.1). DNS functions like a phonebook for the internet, allowing users to access websites using domain names instead of memorizing numerical IP addresses. When a user types a URL into a web browser, the DNS server resolves the domain name to its corresponding IP address, enabling the connection to the desired web server. DNS is an essential part of the internet's infrastructure, ensuring efficient and user-friendly navigation across the web.