Public finance (see public choice) looks at how the government enters the scene. Traditionally, its focus was on taxes, which automatically introduce “wedges” (differences between the price the buyer pays and the price the seller receives) and cause inefficiency. More recently, public finance has reached into the expenditure side as well, attempting to analyze (and sometimes actually to measure) the costs and benefits of various government outlays and programs.
Applied welfare economics is the fruition of microeconomics. It deals with the costs and benefits of just about anything—government projects, taxes on commodities, taxes on factors of production (corporation income taxes, payroll taxes), agricultural programs (like price supports and acreage controls), tariffs on imports, foreign exchange controls, various forms of industrial organization (like monopoly and oligopoly), and various aspects of labor market behavior (like minimum wages, the monopoly power of labor unions, and so on).
It is hard to imagine a basic course in microeconomics failing to include numerous cases and examples drawn from all of the fields listed above. This is because microeconomics is so basic. It represents the trunk of the tree from which all the listed subfields have branched.
At the root of everything is supply and demand. It is not at all farfetched to think of these as basically human characteristics. If human beings are not going to be totally self-sufficient, they will end up producing certain things that they trade in order to fulfill their demands for other things. The specialization of production and the institutions of trade, commerce, and markets long antedated the science of economics. Indeed, one can fairly say that from the very outset the science of economics entailed the study of the market forms that arose quite naturally (and without any help from economists) out of human behavior. People specialize in what they think they can do best—or more existentially, in what heredity, environment, fate, and their own volition have brought them to do. They trade their services and/or the products of their specialization for those produced by others. Markets evolve to organize this sort of trading, and money evolves to act as a generalized unit...