Economic goods are termed scarce when they are "not available in sufficient quantities to satisfy all wants for them." Scarce resources are those that have a limited supply relative to the demand for them. This scarcity means that choices must be made about how the resources are allocated, and that not all wants or needs can be fully satisfied. The concept of scarcity is fundamental to the study of economics, as it is the basis for understanding the concepts of opportunity cost, trade-offs, and efficiency.