Ideal type is an abstract model of a classic, pure, form of social phenomenon. Ideal type is a model concept and does not necessarily exist in exact form in reality. An example of ideal type is Ferdinand Tonnies's dichotomy Gemeinschaft and Gesellschaft.
Tonnies described two opposite, or polar types, of social association, one personal and committed (community) one impersonal and unemotional (society-association). These two formal types then provide a benchmark for the analysis and comparison of actually existing societies. Max Weber also used this method of analysis with his ideal types of bureaucracy, authority and social action.
The Ideal Type and Sociological Theory - Jon Hendricks, University of Kentucky Lexington, Kentucky, C. Breckinridge Peters, University of Kentucky Lexington, Kentucky - Acta Sociologica, Vol. 16, No. 1, 31-40 (1973).
Though widely used in the literature of sociology ideal types have received little systematic explication. One of the difficulties is the ambiguity surrounding the usage of types as theoretical or definitional statements.
The Weberian Ideal-type:
Development and Continuities
Four ideal-type organizational
responses to New Public Management reforms and some consequences