Weber himself wrote: "An ideal type is formed by the one-sided accentuation of one or more points of view and by the synthesis of a great many diffuse, discrete, more or less present and occasionally absent concrete individual phenomena, which are arranged according to those onesidedly emphasized viewpoints into a unified analytical construct...
It is a useful tool for comparative sociology in analyzing social or economic phenomena, having advantages over a very general, abstract idea and a specific historical example. It can be used to analyze both a general, suprahistorical phenomenon (like capitalism) or historically unique occurrences (like Weber's own Protestant Ethics analysis).
To try to understand a particular phenomenon, one must not only describe the actions of its participants but "interpret" them as well. But interpretation poses us a problem for we have to attempt to classify behavior as belonging to some prior "ideal type". Weber described four categories of "Ideal Types" of behavior: zweckrational (rational means to rational ends), wertrational (rational means to irrational ends), affektual (guided by emotion) and traditional (guided by custom or habit).
Critics of ideal type include proponents of the normal type theory. Some sociologists argue that ideal type tends to focus on extreme phenomena and overlook the connections between them, and that it is difficult to show how the types and their elements fit into a theory of a total social system.