The cognitive Internet of Things (Cognitive IoT) is one of the concepts that is accelerating in recent days with high technological advancements in various sectors. Cognitive IoT system is often integrated with other technologies such as cloud computing and big data to deliver better results. These advancements have high decision-making capacity which sometimes, is better than that of humans. The evolution of Cognitive IoT in recent years is enormous. It is also applied in all the domains ranging from smart wearables to healthcare and communication sectors. As the number of devices increases the technologies associated with them are also getting upgraded.