The Domain Name System is the phone book of the internet. When you type a website address like google.com into your browser, DNS translates that human-readable name into a numerical IP address like 142.250.80.46 that computers use to find each other on the network. Without DNS, you would need to memorize long strings of numbers for every website you visit. DNS makes the internet usable by letting people work with names instead of numbers.
The lookup process works in steps. Your browser first checks its own cache to see if it already knows the IP address. If not, it asks the operating system, which checks its cache too. If the answer still is not found locally, the request goes to a recursive resolver, usually run by your internet provider. The resolver asks a root name server, which points it to the correct top-level domain server (.com, .org, .net). That server points to the authoritative name server for the specific domain, which finally returns the IP address. This whole chain typically completes in under 100 milliseconds.
DNS records come in several types. An A record maps a domain to an IPv4 address. AAAA records do the same for IPv6. CNAME records create aliases, pointing one domain name to another. MX records tell email servers where to deliver mail for a domain. TXT records hold arbitrary text data and are commonly used for email authentication (SPF, DKIM) and domain verification. NS records specify which name servers are authoritative for a domain.
Because every internet request starts with a DNS lookup, DNS performance and security matter for everything online. Slow DNS adds latency to every page load. DNS poisoning attacks redirect users to fake websites by injecting bad records into resolver caches. DNSSEC adds cryptographic signatures to DNS records to prevent tampering. Services like Cloudflare DNS (1.1.1.1) and Google DNS (8.8.8.8) offer faster and more secure alternatives to default ISP resolvers. DNS is invisible to most users, but it is one of the most critical pieces of internet infrastructure.