There exist two types of property rights: absolute property rights, e.
g., over material objects, and relative property rights, e. g., contra
ctual rights. The property-rights approach'' deals with the first type
, ''transaction cost economics'' with the second. As for the latter th
e concept of relational contracts is of particular importance, and wit
h it social relations between individuals. It offers an explanation fo
r the overcoming of the unforeseen in a world with transaction costs a
nd hence of the functional efficiency of a private ownership economy i
n the real world. Various examples of application of the economic theo
ry of private property are provided. The market, the firm, financial m
arkets and financial intermediaries, the family, and the state. The me
aning of variants of multivarious private property is thus illustrated
- from the property of individuals in objects, to rights and relation
ships and, last but not least, the property of individuals in themselv
es.