Light absorption is the process by which materials take in light energy rather than reflecting or transmitting it. When light hits an object, certain wavelengths are absorbed depending on the material's properties. This absorbed energy can cause electrons in the material to move to a higher energy state, which can lead to various effects, such as heating or chemical reactions. Different materials absorb light differently, which is why we see various colors. For example, a red apple appears red because it absorbs most wavelengths of light except for red, which is reflected to our eyes. This principle is essential in fields like photovoltaics and photosynthesis.