Fuzzy set theory was developed by Lotfi A. Zadeh in 1965 (Persian Scientist - Born in Azerbaijan). A fuzzy set is a set which an element can have membership in that set with some degrees of membership. Fuzzy set theory is an extension of the classical set theory which in an element is a member of a set or not. Membership degree of an element while it is considered in binary (0 & 1) way is called classical set theory . In comparison, in fuzzy set theory an element can be a member of different sets with some degrees and the membership value is between 0 and 1.  Fuzzy set theory is generalized classical set theory, meaning that classical set theory is a special case in fuzzy set theory when membership of an element is only in one set. Fuzzy set theory is the most useful in today's developing technology, science and engineering. The most important property of fuzzy set theory that made it applicable almost everywhere is flexibility given to machines in decision making. With fuzzy set theory, a machine can  decide based on different situations defined for it. As an example, ABS brakes, Anti-Shakes in cameras, cleaning system in washing machines, speed control in air-conditioners and many other things we use/ see everyday.