The Domain Name System (DNS) functions as the internet's phone book, converting human-friendly domain names (like canada.ca) into the numerical IP addresses computers need to communicate. Every time you visit a website, DNS servers perform this translation invisibly and near-instantaneously. The system is hierarchical: root servers direct queries to top-level domain servers (.ca, .com), which point to authoritative servers for specific domains. DNS infrastructure is critical to internet functioning—outages can make websites inaccessible even when the sites themselves are operational. Cybersecurity concerns include DNS spoofing (redirecting users to malicious sites) and DNS-based attacks. Organizations must properly configure DNS records for their domains, including security features like DNSSEC that verify responses haven't been tampered with. Understanding DNS helps explain various internet issues and security measures.