Consciousness, at its simplest, is awareness of states or objects either internal to one's self or in one's external environment. However, its nature has led to millennia of explanations, analyses, and debate among philosophers, scientists, and theologians. Opinions differ about what exactly needs to be studied, or can even be considered consciousness. In some explanations, it is synonymous with mind, and at other times, an aspect of it.
In the past, consciousness meant one's "inner life": the world of introspection, private thought, imagination, and volition. Today, it often includes any kind of cognition, experience, feeling, or perception. It may be awareness, awareness of awareness, metacognition, or self-awareness, either continuously changing or not. There is also a medical definition that helps, for example, to discern "coma" from other states. The disparate range of research, notions, and speculations raises some curiosity about whether the right questions are being asked.