Consciousness has been famously dubbed the “hard problem” of neuroscience (as opposed to the “easy” problems of, say, how memories are stored and retrieved, or what the neural causes of psychiatric disorders might be). The hard problem is, basically, the question of how the experience of consciousness arises from the chemical reactions and neural connections that make up the brain.
While neuroscience has made tremendous progress in sussing out how the brain works, the mind is still a mystery. Science hasn’t yet figured out how the brain produces the smell of rain, the feeling of joy, and most fundamentally, the sense of being aware that you are aware.