DNS (Domain Name System) is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It translates human-readable domain names (like example.com) into machine-readable IP addresses (like 192.0.2.1).

It can "break everything" because if DNS resolution fails, your computer cannot find the IP address for a given domain name, meaning you can't access websites, send emails, or use any other internet service that relies on domain names, even if your internet connection is otherwise working. Common issues include misconfigured DNS servers, incorrect DNS records, or network problems preventing access to DNS resolvers.