---
title: Top-Level Domain (TLD)
description: An overview of Top-Level Domains (TLDs), their classification (gTLD, ccTLD, etc.), and the structure of the DNS root zone.
---

A **Top-Level Domain (TLD)** is the rightmost segment of a domain name (after the last dot). TLDs are the highest level of the DNS hierarchy below the root.

## TLD Classifications

### Generic TLD (gTLD)

Originally intended for specific use cases, most gTLDs are now open to everyone.

* **Legacy**: `.com` (commercial), `.net` (network), `.org` (organization).
* **New gTLDs**: Thousands of niche extensions like `.app`, `.blog`, `.guru`.
* **Restricted**: Domains like `.bank` or `.pharmacy` require verification of eligibility.
* **Brand**: Closed TLDs for corporations, e.g., `.google` or `.bmw`.

### Country Code TLD (ccTLD)

Reserved for countries and territories (two letters, based on ISO 3166).

* **Examples**: `.uk` (United Kingdom), `.de` (Germany), `.io` (British Indian Ocean Territory).
* **Rules**: Policies vary strictly by country. Some require local residency (e.g., `.no`, `.ca`), while others are marketed globally (e.g., `.tv`, `.ai`).

### Sponsored TLD (sTLD)

Managed by private organizations representing a specific community.

* `.gov` (US Government)
* `.edu` (Accredited US institutions)
* `.aero` (Aviation industry)

### Infrastructure TLD

* `.arpa`: Managed by IANA, used exclusively for technical infrastructure (e.g., reverse DNS lookups).

## Reserved TLDs

Per [RFC 2606](https://tools.ietf.org/html/rfc2606), four TLDs are permanently reserved for testing and documentation to avoid confusion in production environments:

* `.test`
* `.example`
* `.invalid`
* `.localhost`

## See also

- [Top-level domain (Wikipedia)](https://en.wikipedia.org/wiki/Top-level_domain)
- [IANA Root Zone Database](https://www.iana.org/domains/root/db)
