Wikipedia: The Missing Manual

Don’t Take Article Scope as a Given

You’ve picked an article, started in on it, and discovered that it’s getting too long, or one part of it is getting too long. Or, alternatively, you don’t believe can build it up into something reasonably good. If so, rethink the article’s scope. You don’t have to accept what you’re found, when you started on the article, as the definitive boundaries of the article’s scope.

Too Much Content: Spinoffs

Chapter 13 (When an article gets too long) explains how to spin off a section of an article into a new article. That’s the way to go when a section become too long and is about a subject notable enough for an article of its own. Keep this concept in mind as you work on any article: If a section becomes so long that it unbalances an article, if it’s truly notable and not a collection of minor facts—spin it off.

Overlapping Content: Merging

Say that you’ve starting working on the article Thingabobbery, and you notice that another article, Thingabboberists (about the professionals who do thingabobbery for a living), has a lot of overlap in content. Moreover, there aren’t a lot of articles about one that don’t discuss the other.

Wikipedia has a standard solution for overlapping articles—merge them. Merging is a normal editing action, something any editor can do. You’re not required to propose it to other editors, and you don’t have to ask an administrator to help you do it. If you think merging something improves Wikipedia, you can be bold and just do it. ...