Human's desires for goods & services which gives them pleasure & satisfaction. They are goods & services we can do without (not necessary to preserve life), but desire to improve our quality of life (non-essential).
The central concept in economics, referring to the limited availability of economic resources relative to society's unlimited demand for goods and services
Goods or services that are scarce (limited in supply) relative to society's wants - require scarce resources to produce, which could be used to produce something else