The photons bounce off of almost everything and some of them enter our eyes. Those bits that enter our eyes allow us to see. Starting in the 1600s with Sir Isaac Newton , scientists have believed that there are different kinds of photons. Different types give rise to our sense of colors. The different photons are said to have different wavelengths.
Sunlight contains all the different wavelengths of photons.
The visible wavelength colors can be seen when you look at a rainbow. Raindrops acting as natural prisms produce the colors. Just place your mouse pointer at the end of this rainbow and click. We have two main types of photoreceptors called rods and cones. They are called rods and cones because of their shapes.