Hard problem of consciousness

In the philosophy of mind, the hard problem of consciousness (or simply the hard problem) is to explain how and why organisms have qualia, phenomenal consciousness, or subjective experience. It is contrasted with the "easy problems" of explaining why and how physical systems give rise to the ability to discriminate, to integrate information, and to perform behavioural functions such as watching, listening, speaking (including generating an utterance that appears to refer to personal behaviour or belief), and so forth.

Source: Wikipedia — Hard problem of consciousness (CC BY-SA 4.0)