The mind is the totality of psychological phenomena, including thought, perception, emotion, motivation, memory, and learning. It encompasses both conscious processes, through which individuals are aware of external and internal circumstances, and unconscious processes, which can influence individuals without their awareness. Traditionally, minds were often conceived as separate entities that can exist on their own but are more commonly understood as features or capacities of other entities in the contemporary discourse. The mind plays a central role in most aspects of human life but its exact nature is disputed; some theorists suggest that all mental phenomena are private and directly knowable, transform information, have the ability to refer to and represent other entities, or are dispositions to engage in behavior.

In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, and deliberation. But other mental processes, like considering an idea, memory, or imagination, are also often included. These processes can happen internally independent of the sensory organs, unlike perception. But when understood in the widest sense, any mental event may be understood as a form of thinking, including perception and unconscious mental processes. In a slightly different sense, the term thought refers not to the mental processes themselves but to mental states or systems of ideas brought about by these processes.