When collection of thing belongs to certain definition, it is known as Set. When these set shows a degree of membership, it is known as Fuzzy Set. Fuzzy Set theory was given by the Professor Lofti Zadeh , University of California 1965. Copy the link given below and paste it in new browser window to get more information on Fuzzy Set:- http://www.transtutors.com/homework-help/statistics/fuzzy-set.aspx