  There are many books designed to introduce category theory to either a
mathematical audience or a computer science audience. In this book, our
audience is the broader scientific community. We attempt to show that category
theory can be applied throughout the sciences as a framework for modeling
phenomena and communicating results. In order to target the scientific
audience, this book is example-based rather than proof-based. For example,
monoids are framed in terms of agents acting on objects, sheaves are introduced
with primary examples coming from geography, and colored operads are discussed
in terms of their ability to model self-similarity.
  A new version with solutions to exercises will be available through MIT
Press.
