White light is made up of a combination of all visible colors of light. When white light passes through a prism or is refracted, it splits into a spectrum of different colors. This spectrum includes all the colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet.
These colors represent different wavelengths of light, ranging from longer wavelengths for red light to shorter wavelengths for violet light. So, you can say that white light is composed of an infinite number of colors, each with its own specific wavelength.
In terms of additive color mixing, which is commonly used in devices like computer monitors and TVs, white light is created by combining three primary colors of light: red, green, and blue. This is often referred to as the RGB color model. By varying the intensities of these three primary colors, different shades and hues can be created, ultimately resulting in the perception of white light.
It's worth noting that there are also subtractive color models, such as the CMYK model used in printing, where white is achieved by the absence or removal of color pigments rather than the addition of light.