What are the three main categories of TLDs?

The three main categories of top-level domains (TLDs) are:

1. **Generic Top-Level Domains (gTLDs)**: These TLDs are not associated with any specific country or geographic location and are used for various purposes. Generic TLDs are further subdivided into several subcategories:

   - **Unrestricted gTLDs**: These gTLDs have no specific eligibility criteria or registration restrictions, and anyone can register domain names under these TLDs. Examples include .com, .org, .net, .info, .biz, and .name.
   
   - **Restricted gTLDs**: These gTLDs have specific eligibility requirements or registration restrictions defined by the registry or registrar. Registrants must meet certain criteria or qualifications to register domain names under these TLDs. Examples include .edu (for accredited educational institutions), .gov (for U.S. government agencies), .mil (for U.S. military), and .int (for international organizations).

2. **Country Code Top-Level Domains (ccTLDs)**: These TLDs are associated with specific countries or territories and are used to denote the geographic location or country affiliation of a domain name. Each ccTLD is assigned a two-letter country code according to the ISO 3166-1 alpha-2 standard. ccTLDs are managed by national registry organizations designated by the respective countries or territories. Examples include .us (United States), .uk (United Kingdom), .de (Germany), .fr (France), .jp (Japan), and .cn (China).

3. **Sponsored Top-Level Domains (sTLDs)**: These TLDs are specialized domains sponsored by specific organizations or communities for particular purposes. sTLDs may have eligibility restrictions or registration requirements defined by the sponsoring organization. Examples include .gov (for U.S. government agencies), .edu (for accredited educational institutions), .aero (for the aviation industry), .museum (for museums), and .travel (for the travel and tourism industry).

These three categories encompass the majority of TLDs in use on the internet today, each serving different purposes and representing various geographic locations, industries, and communities. Additionally, there are also infrastructure TLDs, such as .arpa, which serve technical purposes and are managed by specialized organizations.