[Apocryphon]

Alternate history fosters systemic thinking to understand outcomes and consider how they could have been altered to create other realities. In doing so, it teaches amateur history, sociology, economics, and other subjects through the reverse-engineering of historical events, to different extents of rigor. Along the way you definitely spot interesting overlooked patterns, such as the long-lived ancient Anglo-Portuguese alliance.

It's also the basis for a lot of creative works. DeviantArt not only plays host to a ton of alternate historical maps, but flags and other graphics.