Mainstream economics refers to the various schools of economics predominantly taught in prominent universitiesis and is used to distinguish certain approaches and schools of thought in economics from heterodox approaches and schools such as the feminist economics and Marxian economics. Economics is the social science that studies the production distribution, and consumption of goods and services. Heterodox economics refers to the approaches or schools of economic thought, that are considered outside of mainstream, that is orthodox economics Feminist economics broadly refers to a developing branch of Economics that applies feminist lenses to economics Note Marxian economics is not restricted to Marxist economics as it includes the economic thought of those inspired by Marx's works who do not identify with Mainstream economists do not, in general, identify themselves as members of a particular school; they may, however, be associated with approaches within a field such as the rational-expectations approach to macroeconomics. Rational expectations is an assumption used in many contemporary macroeconomic models, and also in other areas of contemporary Economics and Game theory Macroeconomics is a branch of Economics that deals with the performance structure and behavior of a national or regional Economy as a whole Currently mainstream economics is dominated by the neoclassical synthesis, which combines neoclassical apporach to microeconomics with Keynesian approach to macroeconomics. Neoclassical synthesis refers to a postwar academic movement in Economics which attempted to absorb the Macroeconomic thought of John Maynard Keynes into 
The term came into common use in the late 20th century. It appears in the influential textbook by Samuelson and Nordhaus, on the inside back cover in the "Family Tree of Economics," which depicts arrows into it from J.M. Keynes (1936) and neoclassical economics (1860-1910). John Maynard Keynes 1st Baron Keynes CB (ˈkeɪnz "cains" (5 June 1883 &ndash 21 April 1946 was a British Economist whose ideas Neoclassical economics is a term variously used for approaches to Economics focusing on the determination of prices outputs and income distributions in markets The term neoclassical synthesis itself also appears in Samuelson's influencial 1955 textbook.  Mainstream economics includes theories of market and government failure and private and public goods. Market failure is a concept within economic theory wherein the allocation of goods and services by a Free market is not efficient. Government failure (or non-market failure) is the public sector analogy to Market failure and occurs when a government intervention causes a more inefficient allocation In Economics, a public good is a good that is non-rivaled and non-excludable. These developments suggest a range of views on the desirability or otherwise of government intervention.
Mainstream economics may employ axioms or postulates in stating a theory. In traditional Logic, an axiom or postulate is a proposition that is not proved or demonstrated but considered to be either self-evident, or subject In traditional Logic, an axiom or postulate is a proposition that is not proved or demonstrated but considered to be either self-evident, or subject Testing the theoretical and empirical implications of those postulates is a standard method of mainstream economics.
Some fields may be described as being partly within mainstream economics, partly within heterodox economics. Heterodox economics refers to the approaches or schools of economic thought, that are considered outside of mainstream, that is orthodox economics Some of them are Austrian economics, institutional economics, neuroeconomics and non-linear complexity theory. The Austrian School, also known as the “ Vienna School ” or the “ Psychological School ” is a heterodox school of economics that advocates Institutional economics, known by some as Institutionalist political economy, focuses on understanding the role of human-made institutions in shaping economic behaviour Neuroeconomics combines Neuroscience, Economics, and Psychology to study how people make decisions Complexity economics is the application of Complexity science to the problems of Economics.  They may use neoclassical economics as a point of departure. Yet, recent research suggests that "neoclassical economics no longer dominates a mainstream economics. "
A countervailing trend is the expansion of mainstream methods to such seemingly distant fields as crime the family, law, politics, and religion. The Family, although recognized as fundamental from Adam Smith on received little systematic treatment in Economics before the 1950s Law and Economics, or economic analysis of law is an approach to Legal theory that applies methods of Economics to law Public choice in economic theory is the use of modern Economic tools to study problems that are traditionally in the province of Political science.  The latter phenomenon is sometimes referred to as economic imperialism.