Categories were introduced to MediaWiki in version 1.3.0 released in 2004.
Categories are basically automatic two-way hyperlinks where when you add a page to a category by adding [[Category:SomeCategory]] to the bottom of the page a link is created to the category from the article and to the article from the category, thus it is a two-way hyperlink.
Categories may be nested i.e. they may contain sub-categories.
Main ways to input categories into articles is to be through using short templates which take care of including the article in all the required categories. Also we will draw in at least 40,000 companies' datas from DBpedia datasets or ontologies.
Other uses may rise. For more reading on this proceed to the Meta-Wikipedias user guide to Categories
 use in Consumerium itself
Preliminary plans are to use categories in Research Wiki pilot for at least Product Groups. Representing each of these as Categories may enable grouping of products and product substitution suggestions. It may help Campaigns (to determine that one doesn't accidentally vote for more then one campaign in each campaign category. Products will be tied to a Product Group category as precise as possible, probably by identifying what services they provide, i.e. all products are bundles of services.
 current categories:
- mediawiki pages that are required or imposed by use of mediawiki software
- deprecated pages are those that no longer play any role in the current design model
 Proposed categories
- POV pages are those that seem to express a particular group point of view, e.g. sysopism, feminism, communism, and may be named with a term used only by the believers in those terms, e.g. only sysopists believe in any "virtual community"
- trollist pages take the NTPOV and usually question ideological or technologist assumptions, and may bite you on the leg for believing groupthink of other POVs
 categories aren't namespaces
- main namespace for terms that have one definition across all of the other namespaces, i.e. the space that has the Main Page in it
- Talk:main namespace to discuss the main namespace
- Special:namespace defined by mediawiki
- Consumerium:namespace for Consumerium Governance Organization decisions/policies that affect how main name space grows and changes, e.g. how troll-friendly it must be
- Develop:namespace for all development decisions and terminology including hardware and integration of software, extremely troll-friendly
- Research:namespace for actual information about companies, products and claims about these
- Publish:namespace for things the CGO actually has published under its own liability