Philosopher David Chalmers identifies the easy and hard problems of consciousness:

The easy problems of consciousness include those of explaining the following phenomena:

the ability to discriminate, categorize, and react to environmental stimuli;
the integration of information by a cognitive system;
the reportability of mental states;
the ability of a system to access its own internal states;
the focus of attention;
the deliberate control of behavior;
the difference between wakefulness and sleep.

The really hard problem of consciousness is the problem of experience. When we think and perceive, there is a whir of information-processing, but there is also a subjective aspect...This subjective aspect is experience.

Fortunately, [Peter] Russell,...says that Chalmers' problem is not just hard; it's impossible. Russell adds..., it does not need to be solved, for it is not a real problem. We do not need to explain how unconscious matter generates immaterial consciousness, because matter is not entirely unconscious, nor is consciousness fully divorced from matter. [ Laszlo p. 146]