Traditional computer programs require precision: on-off, yes-no, right-wrong. However, human beings do not experience the world in this way. Fuzzy systems consist of a variety of concepts and techniques for representing and inferring knowledge that is imprecise, uncertain, or unreliable. Fuzzy systems can create rules that use approximate or subjective values, as well as incomplete or ambiguous data. Statements such as "hot" or "expensive" are not immediately suitable for use by an algorithm. Fuzzy systems provide the means for handling such information by expressing logic with some carefully defined imprecision. Unlike traditional programs that use simple IF-THEN rules, fuzzy systems use statements that closely model the way people think so that these statements can be interpreted by computers as well as human experts.