Thinking is a common process. Cognitive ability includes knowledge, memory and metacognition. Knowledge requires memory. These two are inextricably linked. Parents and teachers need to encourage children to take an active role in their learning and show them how to use what they know to the best advantage. Cognition is primarily a mental process. A successful theory of cognition would answer both the epistemological and biological questions. The purpose is to put forward a theory of cognition, that should provide an epistemological insight into the phenomenon of cognition. The concept of metacognition involves knowledge and control of self and control of the process. A metacognitive process consists of planning, strategies, knowledge, monitoring, evaluating and terminating. The Automation of Cognitive and Metacognitive Processes, Social and Emotional aspects of Metacognition, Domain General Versus domain specific Metacognitive Skills. Metacognition, Intelligence and adaptive behaviour, Ann Brown distinguished between knowledge about cognition and regulation of cognition, Private Speech and Development of metacognition is the models of metacognition.