Metacognition refers to thinking about thinking and includes planning, monitoring, and evaluating cognition. There are three components of metacognitive knowledge: declarative knowledge which is knowledge about things; procedural knowledge which is knowledge about how to do things; and conditional knowledge which is knowledge about when and why to apply cognitive acts. Metacognitive knowledge results from individuals' metacognitive experiences and depends on their metamemory or knowledge about memory. Instruction and practice help develop richer metacognitive and metamemory knowledge over time.