This is a great "back pocket" book - one which can easily be carried around to be read in those times of waiting for the bus, standing in line, etc. Gibbin has divided the book into subjects, each one to two pages long, as he explains science concepts in layman's terms. A sampling of the subjects are plate tectonics, Olber's paradox, and the Jupiter effect. This book is easily understandable to students in both middle and high school and the great majority of adults. A fun book to have and to read.