CategoriesW are a software feature of MediaWiki (the wiki software that powers Appropedia), which enables editors to add pages to automatic listings called category pages.W These help structure a project such as Appropedia by grouping together pages on similar subjects.
A category page lists the articles (or other pages) that editors have added to a particular category. There may also be a section listing the subcategories of that category. The subcategorization feature makes it possible to organize categories into tree-like structures to aid navigation.
Every page on Appropedia belongs in at least one category. It's common for an article to fit into two or more categories. To see the categories in Appropedia:
- Browse the Appropedia:CategoryTree (or start at the top-level category)
- Browse all categories
- Use Special:PrefixIndex to list all categories beginning with a particular string of characters, for example:
 Using categories
If you create a new category, it's best to put it within another category. On the occasions when it doesn't fit in another category, then it is a fundamental category, and should contain the tag [[Category:Fundamental]] as the last line of your new wiki category.
If you are unsure, you can discuss it at the Village Pump.
To start a new subcategory, edit the page Category:Your subcategory name and then at the bottom of your wiki enter the line [[Category:The category name that your subcategory is a part of]].
A glance at the navigation bar shows several collections:
- How tos
And there are more that don't show up in the navigation bar.
All of the collections above are categories, except "Users" (which is a special group due to Appropedia's wiki software). The diagram below is a useful visual aid for discussing how categorization works, but don't take it too literally; attempting to capture the categorization in 2 dimensions is tricky. Refer to it as you read the words below it. Remember that the basic point of categorization is to help users find related content, and this page is meant to describe Appropedia's approach.
(the diagram above is a first pass...I already noticed that "projects" is missing...and probably includes everything!) (sections below will describe in more detail what the categories are, how they overlap, etc.)
 Detailed descriptions of categories
Project pages document actual completed or ongoing implementations of Appropriate Technology, which are categorized under Topics. (Projects that are in the planning stages can be described under Category:Coordination.) They may cover multiple technologies, will typically involve an organization and a location. Depending on the level of detail and the style, a project document may also be a How to page. Note: there is an unfortunate confusing usage of the word "project" that comes with the wiki software; in some contexts "project" refers to the content page associated with a "talk" page, even if that page is not an Appropedia Project category page.
Topic categories help to organize technologies. Some technologies fall into multiple technology topic categories. For example, windmill water pumps may be categorized as being under Category:Water as well as Category:Wind power. Project pages should be categorized under one or more Topic categories, as should most How to and Thesis pages. Organizations which focus on a particular technology area can fall into a topic category. For example, International Rivers Network is in Category:Water
Program pages are intended to describe various organized implementation or educational efforts involving Appropriate Technology or Sustainable Development.
As you would expect, are pages that offer detailed information allowing a reader to implement a particular technology, and would also be categorized under appropriate Topic categories. As mentioned above, Project pages can sometimes be How tos. However, How tos need not be technology focused; How tos can document processes, such as grant application, field assessments, inter-organization engagement, etc. Example: Weld wood
Thesis pages are academic papers related to Appropriate Technology or Sustainable Development. Typically these pages are posted by the authors, and in any case must be posted with permission under the Appropedia:Copyrights. Usually these pages will also be categorized under one or more topic categories.
Users are technically not a category, but a built-in grouping of the wiki software. Users may categorize themselves as being part of an organization, or focused in a particular technology topic.
Organizations are straightforward. Academic institutions, volunteer groups, charitable organizations, NGOs generally, and even governmental groups can be categorized as organizations.
Coordination pages are for managing the actions of several people. These pages can be used to coordinate production of a flyer, or a large project. Example:
Projects and organizations that are located in specific countries (that is, not international) should be placed in a country category. Currently, most of the location categories are countries. As the number of pages grow, it will make sense to add larger and smaller regional groupings, such as continents and subregions of countries, as well as even city categories.
 When should a new category be created?
 Topic categories
If a subtopic has very few articles (say, less than about 5), then it may be better to just use a broader category for the time being.
When there is adequate content and/or more articles, the content can be moved to the more specific category. See Help:Moving a page#Moving a category.
Any organization with its own pages - such as original content and/or its own projects - should have its own category.
Programs and projects with a number of pages can have their own category. If there are is a very small number of pages, it's acceptable to use their organization's category.
 Naming categories
 Use names that make sense to a global audience
For example, avoid use season names in categories. A category name such as "Spring 2006", describing the March-May period, only makes intuitive sense for those north of the tropics, not for those in the tropics or the southern hemisphere. However, if it's part of a program name for a specific school or specific location, e.g. "Springfield Summer School," this may be a suitable category name. The category text, however, should specify the period covered in terms of the calendar (dates or months).
 Linking to categories
There are a few options for linking to categories.
This is useful when you want to tell someone else about a category, and how to add it to a page, for example when writing help pages, or advising someone on their user talk page.
[[:Category:Mexico|pages about Mexico]]
 Moving category pages
 See also
- Category:Appropedia maintenance#Help maintaining the category structure
- Help:Moving a page#Moving a category
- wikipedia:Help:Category - fundamentals of the category feature of the MediaWiki software
- wikipedia:Wikipedia:Categorization - Wikipedia's guidelines for categories
- wikipedia:WP:EIW#Cat - links to many pages about categories, from the Editor's index to Wikipedia
- wikipedia:Wikipedia:Categories, lists, and navigation templates - compares three popular methods to group related pages on a wiki