Black absorbs all of the wavelengths of light, converting them into heat. At the same time, black does not reflect any of the other colors.
Black absorbs every wavelength of light without reflecting any back. This is what makes it appear as black, which is the absence of color being visible. This also means that black absorbs the most heat of all, since light is connected to heat. Black contains all of the wavelengths of light within it. Conversely, white reflects all wavelengths of light, and it absorbs the least light and heat.
The colors that are seen by the human eye are a result of electromagnetic waves from the sun being reflected by an object. Specific wavelengths are reflected and seen, while others are absorbed and not seen. Heat is another result of electromagnetic waves, and different colors absorb heat in different amounts.
This translates to practical purposes when considering the color of clothing, cars, and other items. For example, a person wearing a black shirt on a hot day will likely be uncomfortable, as it will absorb more heat from the sun and the entire wavelength spectrum of light. The reflection and absorption of light is useful in many practical applications, such as solar panels, solar cells, lasers and cameras.