Related article usually helps a user read about similar content or content that matches their interests, however Wikipedia does not have a option to show you related articles while you are browsing around.

Smarter Wikipedia is a Firefox add-on that will add a tab displaying related articles relevant to the current content you are browsing. Pretty useful for discovering content without having to break your head searching for it.

In addition to that, the Smarter Wikipedia add-on also adds a context menu, allowing you to directly search Wikipedia for the text you have selected currently.

Download Smarter Wikipedia ^[1]