Within these pages are several types of picture puzzles: Spot the difference; find one changed photo among six; reassemble a cut-up image; each presented in a variety of categories. Within each category, puzzles are presented in increasing difficulty levels. Alongside each, solvers can compare their time to that of expert puzzlers and check off each difference as they spot it. Researchers have shown that games like these keep your brain sharp, challenge your powers of observation and train your eye to notice the smallest of details. And, you'll have fun while reaping the benefits. It a win-win!