Economics is the study of production, distribution, and consumption of goods and services. A main problem in economics is scarcity, which means there are not enough resources to satisfy unlimited wants. Economics focuses on how people and governments decide how to satisfy unlimited wants with limited resources. Resources include natural resources from the land, capital resources used for production, and human resources in the form of physical and mental labor. When decisions are made, there is always an opportunity cost, which is the value of the best alternative given up. Supply and demand interact to determine price, with demand representing what consumers are willing and able to buy and supply representing what producers are willing to provide.