---
title: TLD (トップレベルドメイン)
slug: Glossary/TLD
tags:
  - Glossary
  - Web
  - WebMechanics
translation_of: Glossary/TLD
---
<p>TLD (トップレベルドメイン)は、インターネットの階層的な {{Glossary("DNS")}} (ドメインネームシステム) で最も一般的な {{Glossary("domain")}} です。TLD は {{Glossary("domain name")}} の最後の要素です。例えば、<code>developer.mozilla.org</code> の "org" です。</p>

<p>{{Glossary("ICANN")}} (Internet Corporation for Assigned Names and Numbers) designates organizations to manage each TLD. Depending on how strict an administrating organization might be, TLD often serves as a clue to the purpose, ownership, or nationality of a website.</p>

<p>Consider an example Internet address: <code>https://developer.mozilla.org</code><br>
 Here org is the TLD; mozilla.org is the second-level domain name; and developer is a subdomain name. All together, these constitute a fully-qualified domain name; the addition of https:// makes this a complete URL.</p>

<p>{{Glossary("IANA")}} today distinguishes the following groups of top-level domains:</p>

<dl>
 <dt>country-code top-level domains (ccTLD)</dt>
 <dd>Two-character domains established for countries or territories. Example: <em>.us</em> for United States.</dd>
 <dt>internationalized country code top-level domains (IDN ccTLD)</dt>
 <dd>ccTLDs in non-Latin character sets (e.g., Arabic or Chinese).</dd>
 <dt>generic top-level domains (gTLD)</dt>
 <dd>Top-level domains with three or more characters.</dd>
 <dt>unsponsored top-level domains</dt>
 <dd>Domains that operate directly under policies established by ICANN processes for the global Internet community, for example "com" and "edu".</dd>
 <dt>sponsored top-level domains (sTLD)</dt>
 <dd>These domains are proposed and sponsored by private organizations that decide whether an applicant is eligible to use the TLD, based on community theme concepts.</dd>
 <dt>infrastructure top-level domain</dt>
 <dd>This group consists of one domain, the {{Glossary("ARPA", "Address and Routing Parameter Area")}} (ARPA).</dd>
</dl>

<h2 id="Learn_more">Learn more</h2>

<h3 id="General_knowledge" style="line-height: 24px;"><strong>General knowledge</strong></h3>

<ul>
 <li>{{Interwiki("wikipedia", "TLD")}} on Wikipedia</li>
 <li><a href="http://www.iana.org/domains/root/db">List of top-level domains</a></li>
</ul>