Long Earth series (Terry Pratchett and Steven Baxter)
 

I love this series. It's set in the near-future, and is about what happens when humans gain the ability to "Step" between an infinite number of parallel Earths, with only the original having human life.

As the books go on we see communities develop in the Stepwise worlds; meet "trolls", "elves", and " kobolds", intelligent beings who share common ancestry with humans; basically, all the world building and character development (I love Maggie Kauffman) is more interesting than the plots/content of the books' blurbs, but they're all fantastic, highly recommended!


(Not finished Long Cosmos yet though)