"Nudge" theory is one of the greatest achievements in the field of behavioral economics in the last decade. The theory explains how to apply the "architecture of choice" in a clever way, in encouraging people to make decisions that will have a positive impact on their lives. The theory does not deny the classical economy, but helps her in further development by showing how people work. It concludes that human beings are not homo oeconomicus, and that they are often prone to avoid making some more complicated decisions or decisions where they have a wide variety of options. It shows that, with the knowledge of people thinking, a small nudge can mean in the long run in different aspects of everyday life - finance, investment, savings, health care, traffic, environmental protection, marriage, friendship. The "Nudge" theory has already begun to apply in many countries of the world, particularly in the United States, where it has already shown certain results. Nudge can not be a solution to all problems, namely nudges have the highest degree of efficiency when they are combined with other measures such as laws and regulations.