Physicalism is a philosophical viewpoint asserting that everything that exists is ultimately physical in nature. This means that all phenomena, including thoughts, emotions, and consciousness, can be explained in terms of physical processes and properties. In essence, physicalism posits that there is no non-physical substance or realm beyond the physical world. According to physicalism, mental states are closely tied to brain states, suggesting that our experiences and feelings arise from the workings of the brain. This perspective aligns with scientific approaches in fields like neuroscience and psychology, which seek to understand human behavior and cognition through physical explanations.