The document discusses the concept of nudge design, which refers to using subtle influences or defaults to guide people's choices in a predictable way without forbidding any options. It provides examples of how framing, default biases, and loss aversion can influence decisions and tips on applying these principles in design. Finally, it considers the ethical implications of nudging and offers choices for designers in either ignoring behavioral influences, openly participating to shape behavior responsibly, or quietly manipulating users.