Metacognition is thinking about thinking, or, the high-level cognitive process that allows individuals to monitor and to respond to mental states. Metacognition, as described by Nelson and Narens (1990), is composed of two levels: an object level and the meta level. The object level contains lower level cognitive processes. The meta level contains representations of the lower level processes. Monitoring describes the flow of information from the object level to the meta level, and the updating of the representations contained in the meta level. Control described the flow of information from the meta level to the object level in the form of direction (e.g., changing of behavior, orienting of attention, etc).
Nelson, T., & Narens, L. (1990). Metamemory: A theoretical framework and new findings. The Psychology of Learning and Motivation, 26, 125–173. http://doi.org/10.1016/S0079-7421(08)60053-5