Wikipedia:Category namespace

Categories are normally found at the bottom of an article page. Clicking a category name brings up a category page listing the articles (or other pages) that have been added to that 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.

The term category does refer to both the title of a category page—the category pagename—and the category itself. Keeping this in mind while reading about categorization, plus learning a category page layout is a worthwhile investment in research techniques. (See also the search box parameter "incategory".) The layout of a category page is mostly text, but see about displaying category trees below.

A category is usually associated with a category page in the "Category:" namespace. A category page contains text that can be edited, like any other page, but when the page is displayed, the last part of what is displayed is an automatically generated list of all pages in that category, in the form of links. Other category pages which appear in this list are treated separately, as subcategories.

A category name can be any string that would be a legitimate page title. It cannot begin with a lower-case letter. If the category name given in a category declaration begins with a lower-case letter, then it is interpreted as if it were capitalized.

Hidden categories are not displayed, except as described below under Hiding categories.

A "category page" is any page in the Category namespace. They each act as a category, and are termed a "category". The category page has one section titled Subcategories listing other "categories", and one section titled Pages, listing pages as categorized (in other namespaces). New categories are created by creating a page in the Category namespace.

A category page can be edited like any other page. However, when it is displayed, the editable part of the page is followed by automatically generated lists of pages belonging to the category, as follows:

The items in the lists all link to the pages concerned; in the case of the images this applies both to the image itself and to the text below it (the name of the image).

For the way in which the lists are ordered, see Sort order below. The first and second lists are divided into sections, according to the first character of the sort key. These initial characters are displayed above the sections. To suppress these, make all sort keys start with a space.

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