The study of economics can be divided into two branches: micro and macro. Microeconomics is the study of how different economic agents interact. Macroeconomics is the study of how a society of economic agents behave as a whole.
To put it more concretely: say you and I own bodega shops across the street from each other.
Microeconomics would be concerned about how we as individual firms behave. As rational actors, what do I sell in response to what you sell? What are your prices in response to my prices? Should I stay in business when I know I won’t make a monopoly profit as long as I have you as competition? Will customers buy what we’re selling?
Macroeconomic questions would be more concerned with how society-wide factors affect all businesses. What effects do tariffs, regulations, subsidies, technological innovations and other far-reaching phenomena have on all shops in general? I.e. how does it affect interest rates, employment rates, income per capita and other economy-wide metrics that are relevant to the success of our businesses?
While these are natural questions that arise, the general focus of both branches is about the allocation of resources. The decisions we make when we compete and the consequences we face from economy-wide forces have an impact on the well-being of society. They determine the quantity and price of goods and services, and whether or not we choose to produce and consume them.
This crash course is on microeconomics. I will start by giving more nuance to Supply and Demand, and will eventually veer off on to insights from game theory. After this course, you should have a relatively deep understanding of how economic agents tend to behave, as well as the consequences of their actions.