A Top-Level Domain (TLD) is the rightmost segment of a domain name that appears after the final dot. It represents the highest level in the Domain Name System hierarchy. Every domain name must have exactly one TLD.
TLDs fall into two main categories: Generic Top-Level Domains (gTLDs) like .com, .org, .net, and .edu, which are available globally; and Country-Code Top-Level Domains (ccTLDs) like .uk, .de, .jp, which are reserved for specific countries or regions.
When you register a domain—say, example.com—you're actually registering a second-level domain (example) under the .com TLD. The TLD is operated by a registry operator, which maintains the authoritative list of all domains registered under it and delegates them to nameservers you specify. Your domain registrar acts as the intermediary between you and the registry.
TLDs also include newer extensions like .app, .dev, .cloud, and hundreds of others approved by ICANN. Each TLD has its own registration rules and policies—some require specific eligibility criteria, while others are open to anyone.
The TLD is critical to DNS resolution: when you type example.com into a browser, the DNS resolver first queries the root nameservers to find which nameservers handle the .com TLD, then queries those servers for the A record or other DNS records for example.com.
TipThe TLD alone (.com, .org) cannot be registered or used as a website—you must always pair it with a domain name (example.com). The combination of the domain name and TLD is what forms a registrable entity.