Economics does not have sharply delineated boundaries, but the domain has been defined broadly, and differently, from time-to-time. Currently, the contents of economics can be divided into the following broad areas: macroeconomics, microeconomics, and development economics. Most economists specialize in one or more of the more narrowly defined branches of economics. They can be further classified as "tool makers" or "tool users." Tool makers typically work at the discipline's frontier, formulating new theories and devising new techniques of analysis. Most economists are tool users who apply existing knowledge to assess economic problems and recommend change. The foundations of economics are being modified constantly by the tool makers. The recipients of the Nobel Memorial Prize in Economic Science for the years 1969-1987 are listed along with their accomplishments. The kinds of research which interest economists can be seen in the record of publications. Hundreds of periodicals are devoted primarily to the publication of research by economists. Several examples illustrate the analytical bases of economists' policy recommendations. Discussions of individuals and households, the labor market, business firms and efficiency, pricing of natural resources, environmental costs, monopoly and competition, macroeconomic policy, international economics, and comparative economic systems are included. Two tables detail the subject matter distribution of published manuscripts in the "American Economic Review," 1981, 1982, 1986, and 1987, and doctoral dissertations in economics, 1982 and 1987. (GEA)