For complex, ill-defined problems, where the uncertainty lies, fuzzy logic is the best suitable methodology to work with. We can achieve a certain level of accuracy and precision by accepting uncertainty. An Intuitionistic fuzzy logic represents imperfect knowledge that lies while dealing with real-life problems. For example, in decision making human opinion has two or more answers such as "may not be", "might be" etc. In such a case human opinion is not firm or has some hesitancy in decision making. An intuitionistic fuzzy logic system can deal with this hesitancy and uncertainty that appears in the real world problems. This paper reviews on intuitionistic fuzzy set, its operations, intuitionistic fuzzy logic system and different applications with a case study in healthcare diagnosis.