The article "Auctions: Theory and Practice" is a simple guide to understanding how auctions work and how they are used in economics. It explains auction theory in an easy-to-understand way and gives examples of how it is applied in real life. The book can be used for courses on auction theory and design. It shows how auction theory can help answer different economic questions and discusses how auctions are designed in practice. The article also talks about the 3G mobile-phone license auctions, which were worth billions of dollars. The writing is not technical, making it accessible to a wide audience.