Hey as Scarcity (also called paucity) is the fundamental economic problem of having seemingly unlimited human wants in a world of limited resources.

Scarcity Definition
Scarcity refers to the basic economic problem, the gap between limited – that is, scarce – resources and theoretically limitless wants.
This situation requires people to make decisions about how to allocate resources efficiently, in order to satisfy basic needs and as many additional wants at possible

Condition
The condition of scarcity in the real world necessitates competition for scarce resources, and competition occurs "when people strive to meet the criteria that are being used to determine who gets what.
The price system, or market prices, are one way to allocate scarce resources. "If a society coordinates economic plans on the basis of willingness to pay money, members of that society will to make money
If other criteria are used, we would expect to see competition in terms of those other criteria

Concept
In cases of monopoly or monopsony an artificial scarcity can be created.
Scarcity can also occur through stockpiling, either as an attempt to corner the market or for other reasons.
Temporary scarcity can be caused by (and cause) panic buying

Example
Although Air is more important to us than gold, it is less scarce simply because the production cost of air is zero.

Gold on the other hand has a high production cost. It has to be found and processed, both of which require a great deal of resources.
Additionally, scarcity implies that not all of society's goals can be pursued at the same time; trade-offs are made of one goal against others.
In an influential 1932 essay, Lionel Robbins defined economics as "the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses.