Philosophy
Have you ever tried to describe the color red to someone who suffers from protanopia, deuteranopia, protanomaly, or deuteranomaly? It is nearly impossible since those who are red-green color blind are missing the corresponding photoreceptors. The experience of seeing red is so familiar to those who have experienced it. And that type of experience, one which is difficult to communicate, does not change based on other experiences, is unique to the individual experiencing it, and immediately recognized, is qualia.