by Orson Scott Card
This book is amazing. I have read this book more times than i can remember and will reread the first three books in this series about every other year. If you have not yet discovered the awesome amazingness that is the Enderverse yet then hold onto your pants and get reading.
Ender's game takes place after the first Formic War, the Buggers have attacked Earth in an attempt to terraform it, problem is they didn't realize humans were intelligent. Ender is part of a group of highly intelligent children who are being trained and formed into the perfect soldiers and commanders so that we can take the fight to the Buggers' home worlds. Intense and thought provoking Ender's Game is in a class of it's own.
Read this now! like RIGHT now!