|This is an information page that describes communal consensus on some aspect of Wikipedia norms and practices. It is intended to clarify the type of article known as an "outline". This is not a Wikipedia policy or guideline; please defer to such in a case of inconsistency with this page.|
|This page in a nutshell: An outline is a list article, arranged hierarchically, that helps a reader learn about a subject quickly, by showing what topics it includes, and how the topics relate to each other. Outlines on Wikipedia combine the benefits of tables of contents, site maps, and glossaries. The system of outlines are also linked together hierarchically. The Wikipedia:Contents/Outlines is an entryway to this system.|
Outlines on Wikipedia are stand-alone lists designed to help a reader learn about a subject quickly, by showing what topics it includes, and how those topics are related to each other.
The term "outline", as used here, is short for "hierarchical outline", which is a type of hierarchical list arranged in levels using indents. An outline is a type of tree structure, designed to graphically convey subjects' connectedness, showing the parent–offspring relationships between topics, and their subtopics. Because using "Hierarchical outline of..." makes article titles too long (e.g., "Hierarchical outline of the Central African Republic") we use the short form "Outline of...". This is consistent with how the academic community and other encyclopedias refer to hierarchical outlines.
Due to the software features used on Wikipedia, outlines here use subheadings and bullet-list indentation to convey hierarchy. Entries may be in the form of topics (terms) or statements (sentences) or a combination of the two (using annotations). Entries that have a corresponding article are linked to that article.
General reference encyclopedias vary in their application of hierarchical outlines, including Wikipedia's two main competitors. The World Book Encyclopedia has traditionally provided a sparse outline at the end of each of its articles, while the Encyclopædia Britannica's approach has been to provide an extensive stand-alone Outline of Knowledge divided into many numbered subject sections in its Propædia volume. Wikipedia has correlates to both of those implementations: WP article TOCs compete with World Book's outlines, while a Wikipedia outline article will compete with a Britannica Propædia section, to scope the same subject.
While portals are collections of excerpts, sort of like the Reader's Digest, outlines are more like site maps. But with the addition of annotations, and by virtue of the hierarchical arrangement of their entries, outlines on Wikipedia go beyond being mere site maps and are evolving into classified glossaries.
Wikipedia's outlines are kind of like restaurant menus. They help you select what to consume next.
Outlines on Wikipedia combine the benefits of tables of contents, site maps, and glossaries. They provide a more organized presentation of a subject's subtopics than either articles or portals. This makes the title subjects faster to navigate, and allows narrowing one's study to desired areas even when the names of the topics one is looking for are unknown. Outlines also make subjects easier to learn by virtue of being knowledge structures, due to the information conveyed within the structures themselves.
Regular articles (which are prose arranged in paragraphs) are intended as introductions to their respective subjects. They make for a good read, but they aren't all that effective for browsing or navigating an entire subject. An outline is intended to provide more direct access to Wikipedia's coverage of an entire subject via linked branches.
Wikipedia's coverage of a subject goes far beyond the scope of the prose article on that subject. (For example, there are over 30,000 articles on mathematics). The arbitrary network of links embedded in paragraphs throughout a subject do not map out that subject very well at all, and they can't because the ability of the prose format to do this is limited. For lists, however, mapping subjects is a strength, especially for outlines.