Wikipedia:Scope

Scope is what you can expect to find in Wikipedia and its articles. Wikipedia is not intended to include everything.

Scope of Wikipedia
Wikipedia is an encyclopedia. Encyclopedias summarize knowledge, rather than try to contain all of it. While the promotional slogan "the sum of all human knowledge" is sometimes used to describe Wikipedia or its goal, that is an exaggeration. The world's knowledge is vast. Bigger than the collections of all libraries. Larger than the works of all publishing companies combined. Greater than the Internet. It is not Wikipedia's goal to duplicate all the effort that went into creating and maintaining those resources. Instead, Wikipedia provides introductions and overviews of notable subjects, to help alleviate the need to sift through all knowledge to understand the essentials. Once readers are familiar with the basics of a subject, and its jargon, they are better prepared to study and understand the rest of it.

Wikipedia's scope, what it should and should not include, is defined in its content policies and guidelines. For details, refer to the pages listed in the navigation box to the right.

Scope of articles
The scope of an article is the range of material that belongs in the article, and thus also determines what does not belong in it (i.e., what is "out of scope").

The title together with the lead section (ideally, the introductory sentence or at least the introductory paragraph) of an article should make clear what the scope of the article is.

Effects
All material that is notable, referenced and that a reader would be likely to agree matches the specified scope must be covered (at least in a summarize fashion).

What reliable sources say about material that is out of scope for the decided-upon subject is largely irrelevant to that article and can be removed or moved to another article.

Choosing the scope

 * Article scope, in terms of what exactly the subject and its scope is, is an editorial choice determined by consensus.
 * When the name of an article is a term that refers to several related topics in secondary reliable sources, primary topic criteria should be followed to determine if any of the uses of that term is the primary topic. If so, then the scope of the article should be limited to, or at least primarily, cover that topic. For example, the article "Cat" is limited in scope to the primary topic for cat, the domestic cat (which is a redirect to "Cat"), even though lions and tigers are considered to be "cats" in the broad sense of that term.
 * Looking at what scopes other encyclopedias have chosen can often be useful.
 * Scope is different from balance. Balance has to do with how much of the article covers any given subject. Scope has to do with whether the subject should even be covered at all.
 * Artificially or unnecessarily restricting the scope of an article to select a particular point of view on a subject area is frowned upon, even if it is the most popular point of view. Accidental or deliberate choice of a limited scope for an article can make notable information disappear from the encyclopedia entirely, or make it highly inaccessible. Since the primary purpose of the Wikipedia is to be a useful reference work, narrow article scopes are to be avoided.