Synthesized answer
The key concept in "Nudge" is the application of the science of choice to influence people's decisions. This is done in a way that guides them towards choices that are beneficial for them, without taking away their liberty to choose [Passage 1].
The authors, Thaler and Sunstein, describe this as a "groundbreaking discussion" on how to "nudge people toward decisions that can improve their lives without restricting their freedom of choice" [Passage 1]. The passages do not provide further explanation of what "nudge" means in practice or further details on the "science of choice" or the specific types of decisions that can be improved.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Nudge by Richard H. Thaler, Cass R. Sunstein Description: Thaler and Sunstein offer a groundbreaking discussion of how to apply the science of choice to nudge people toward decisions that can improve their lives without restricting their freedom of choice. Categories: Business & Economics Pages: 305 Snippet: Thaler and Sunstein offer a groundbreaking discussion of how to apply the science of choice to nudge people toward decisions that can improve their lives without restricting their freedom of choice.