Introduction to Economics
Economics is the social science studying the production, distribution and consumption of goods and services. ... At its most basic, however, economics considers how a society provides for its needs. Its most basic need is survival; which requires food, clothing and shelter.
First is Robbins' famous all-encompassing definition of economics that is still used to define the subject today: "Economics is the science which studies human behavior as a relationship between given ends and scarce means which have alternative uses."
You implicitly understand scarcity, whether you are aware of it or not. It is the most basic concept in economics, and is more of a solid fact than any abstraction. Simply put, the world has limited means to meet unlimited wants, so there is always a choice to be made.
Economics is the social science which studies economic activity: how people make choices to get what they want. It has been defined as "the study of scarcity and choice" and is basically about individual choice.