Differences between Wikipedia, Wikimedia, MediaWiki, and wiki/ja

MediaWiki、Wikimedia (ウィキメディア)、Wikipedia (ウィキペディア)、wiki (ウィキ) の違いに戸惑っていますか?

ウィキ
Wiki is a generic term which is used to describe a certain kind of collaborative website that can be edited by any user and/or visitor; it is not a proper noun.
 * wiki (as an adjective), "the wiki way", and the antonym un-wiki are also used to describe the community-oriented philosophy that goes with such a system (e.g. "that's not a very wiki way of doing things").
 * Wiki (with a capital 'W') is an incorrect term, although it has sometimes been used to refer to either Wikipedia or the Portland Pattern Repository (also known as WikiWikiWeb), which was the first wiki to be created.
 * wiki software and wiki engine are terms referring to pieces of software that power wiki-based websites. There are many different types of wiki software; some very simple, others with advanced features. See also: Wikipedia's entry on "wiki software".

''完全な詳細情報はウィキペディアの項目「ウィキ」を参照してください. ''

ウィキメディア
Wikimedia is the collective name for the Wikimedia movement, revolving around a group of inter-related projects, including Wikipedia, Wiktionary, Wikiquote and others, which aim to use the collaborative power of the Internet, and the wiki concept, to create and share free knowledge of all kinds.
 * The term Wikimedia servers is often used, referring to the computer hardware on which all Wikimedia projects are hosted.
 * ウィキメディア・ドイツ (Wikimedia Deutschland)、ウィキメディア・ロシア (Wikimedia Russia) などは、ウィキメディア財団の一部ではなく、財団と通常は友好関係にある組織です.
 * ウィキメディア メタウィキ (Wikimedia Meta-Wiki) は、よくメタ (Meta) と呼ばれ、これはすべてのウィキメディア・プロジェクト群に影響する問題点について議論するのに使用されるウィキです.  About/ja もご覧ください. 
 * Meta を MetaWiki と混同しないでください. これは検索エンジンであり、ウィキメディアのプロジェクト群の一部ではありません.

ウィキペディア
Wikipedia is a Wikimedia project that is a global, free and multilingual internet encyclopedia. It is the oldest, and largest, Wikimedia project, predating the Wikimedia Foundation itself. Wikipedia is a wiki that runs on MediaWiki.

MediaWiki
MediaWiki is a particular wiki engine, that is developed for and used by Wikipedia and the other Wikimedia projects. MediaWiki is freely available for others to use (and improve), and it is in use by all sorts of projects around the world.

動画

 * [//www.youtube.com/watch?v=gXD1TRGafQ0 The State of Wikipedia] (YouTube)