感觉 (gǎn jué) is both a noun ('feeling') and a verb ('to feel, to perceive'). As a verb, it overlaps with 觉得 (jué de, 'to think that') — 感觉 is more about a sensory or intuitive feeling, while 觉得 is more about an opinion or judgment. 感到 (gǎn dào) is used for specific emotions or sensations (e.g., 感到高兴), whereas 感觉 can be more general.