This book examines the economy as an evolving entity and develops a new and coherent approach to the classification of economic systems. It demonstrates how the components of a decision-making system and the properties of a functioning economy are intrinsically linked. A well-functioning economy is shown to depend chiefly on 'correct' decisions. These in turn depend on an efficient decision-making system, an appropriate mix of markets, organizations and governments, and an optimal combination of the four enforcing mechanisms of a modern economic system: custom, command, competition and cooperation. Although this book is primarily about economics, non-economic considerations, including politics and ethics, are brought into the analysis. The most important decisions in life include choices between economic and non-economic issues. Hence, one of the aims of this book is to provide a conceptual framework to cope with these choices. The book also attempts to establish some plausible conditions for well-functioning economy and a 'just society'. This thoughtful book will be of interest to economists of economic theory and economic systems as well as policymakers in both the private and public sectors.