Microeconomics is a study of how to best solve the basic economic problem, which is how to allocate scarce resources given unlimited wants.
Resources, also known as factors of production, are scarce and can be categorized as capital, enterprise, land, and labor.
Capital in economics does not mean money, but man-made aids to production such as machinery, tractors, and factories.
Enterprise refers to entrepreneurs or risk takers who innovate and produce goods and services to make profits.
Land in economics refers to natural land like farmland and rainforests where goods can be produced or goods can be taken.
Labor in economics refers to human resources, workers that can produce goods and services.
The world does not provide an infinite amount of these resources, hence they are scarce.
In a market economy, businesses decide based on consumer demand how to produce and for whom to produce.
The government can step in and help out in a market economy, but if you can afford it then you get it.
Opportunity cost is the cost of the next best alternative foregone when a choice is made.
If the value of our current choice is greater than the value of our opportunitycost, then we have made an excellent decision.
If the value of our opportunity cost is greater than the value of our current choice, then we have made a bad decision and should allocate resources towards our opportunity cost instead of allocating resources towards our current choice.
Production possibility frontiers can be used to analyze choices in more detail.