A fun and interactive look at codes throughout history, from Caesar's battlefield message to contemporary hackers.Codes can carry big secrets! Throughout history, lots of good guys and lots of bad guys have used codes to keep their messages under wraps. This heavily designed, fun, flippable nonfiction features stories of hidden treasures, war-time maneuverings, and contemporary hacking while explaining the mechanics behind the codes in accessible and kid friendly forms. Sidebars call out activities that invite the reader to try their own hand at cracking and crafting their own secret messages. This is the launch of an exciting new series that invites readers into a STEM topic through compelling historical anecdotes, scientific backup, and DIY projects.