Wikipedia, the free encyclopedia is huge. The English version alone is currently at almost 3.6 million articles. One of the advantages of it being online is that no matter how big it is you can view the newest version of only the parts you are interested in without having to download the whole thing. But what if you did want to download it and use it offline?
You could download a copy of Wikipedia Static. It is composed of static HTML pages so it is quite big (~17GB compressed). It is also getting old, it was last generated in June of 2008. You could also setup a mirror of Wikipedia.
Fortunately, there are a few other options for offline viewing of Wikipedia content. The following are a few of my favourites:
Kiwix – http://kiwix.org
Images, Tables and Text but only ~45,000 articles from Dec 2010, 3.7GB, GPL3, OSX, Windows, Linux.
Kiwix is client software for Linux, OSX, or Windows that uses an open data format for mediawiki developed by the openZIM project. The software includes a server mode for sharing on an intranet. The 3.7GB, Dec 2010 snapshot of Wikipedia consists of about 45,000 articles considered to be core articles tagged as part of the Wikipedia 1.0 Project. There are other zim format files available in other language versions of Wikipedia and also Wikipedia:Books. It is a newer project and format so additional zim formatted documents will likely become available as support and awareness grows.
Aard Dictionary – http://aarddict.org/
Text, Math and Tables, no Images, Mar. 12, 2010, 7.2GB, GPL3, OSX, Windows, Linux, Android, Nokia Maemo 5.
Aard Dictionary is a multi-platform word lookup program that supports large dictionaries and Wikipedia. The 7.2GB Wikipedia snapshot from March 12, 2010 contains more articles than Kiwix it does not support audio, video and images (except for images rendering math). It also doesn’t support all of the navigation features of Wikipedia. It is quite fast, however, and also supports a variety of other reference material such as Wikitionary, WikiQuote, Wikispecies, WordNet, The Collaborative International Dictionary of English, The Jargon File and other language versions of Wikipedia.
WikiReader – http://thewikireader.com/
Text only, no Images, Tables or Math, Jan. 15, 2011, 4.3GB, GPL3.
The WikiReader is a handheld device and open software that allows you to take Wikipedia with you. This device supports text only and searches are limited to article titles. You can download free quarterly snapshots of Wikipedia to a microSD flash memory card that plugs into the device or pay for a subscription shipped on memory cards. Other language versions of Wikipedia, Wikitionary, WikiQuote, and Project Gutenberg and WikiTravel are also available. The WikiReader I purchased included a 4GB microSD card which is big enough for the Summer 2010 snapshot of English Wikipedia but the newer snapshots will require purchasing a larger microSD card. The 2 AAA batteries that power this device are expected to last about 90 hours so this little device is very careful with power consumption.
These are three solid options for carrying around a pretty good sized encyclopedia without all the bulk. The first two are free so I would recommend using both of them. Perfect for the laptop or netbook. The third is small, very reasonably priced, very power efficient and ready for travel.
* Edited April 13, 2013 – Updated url for Wikipedia Static and other Wikipedia dumps.