Color is the appearance of objects caused by the different qualities of light that they reflect or emit. Light is required to see color. When light strikes on an item, certain colors bounce off of it while others are absorbed. Our eyes can only see colors that have been bounced off or reflected. So color depends on how things look from a distance versus up close.
When light hits most materials, some of it is reflected back and some is absorbed. The amount that's reflected changes depending on the material itself. For example, if you look at an orange from a distance, you'll see red because red is what's left over after all the orange has been reflected away from you. If you get closer to the orange, you'll see that there's more than just red left behind - there are also yellow and green! This is because those are the colors of light that were not absorbed when looking at the orange from far away.
Things get more complicated when more than one material is involved. Let's say you have an object made out of glass and metal. When light hits it, some of it is reflected back and some is refracted (bent). Reflected light will be colored by the material it bounces off of while refracted light will be colored by the material it passes through. In this case, it would be like seeing red from a distance followed by blue as you get closer.
Our brain determines what hue we are seeing based mostly on one factor: the light that enters our eyes. White light is made up of all hues of radiation. When an item receives light, some wavelengths are absorbed while others are reflected. The ones that it reflects are the ones that we can see in color. For example, if you were to hold up a piece of white paper to the sun, it would quickly take on a yellow color because most of the white light is being reflected back out into space rather than being absorbed by the paper.
When light hits objects that contain different levels of pigment (such as the whites of your eyes or skin), some of it is reflected back and some is transmitted through. The amount that's reflected back depends on how much pigment there is in the object viewing the light. If there is a lot of pigment, most of the light will be reflected back; if there is little or no pigment, most of the light will pass through.
People have different levels of sensitivity to different wavelengths of light, which is why some people see red and others see green. The part of the brain that detects color uses information from all three types of receptors to determine what hue is present. It does this by comparing the intensity of each wavelength to the other two.
Objects seem different hues because they absorb some colors (wavelengths) while reflecting or transmitting others. The wavelengths that are reflected or transmitted are what we experience as colors. For example, if you look at a yellow pencil, you see the color yellow because it absorbs the blue and green wavelengths in light and only reflects the red wavelength back to your eye.
The color of an object depends on the wavelengths of light that are absorbed versus those that are reflected. An equal amount of all wavelengths will be absorbed equally, resulting in white light; most wavelengths will be transmitted through the object, resulting in blackness; or some wavelengths will be reflected back towards your eye, resulting in coloration.
Colors also vary because objects reflect/transmit certain frequencies of light and not others. The more transparent an object is, the higher frequency components of light will pass through it without being affected. Colors appear more saturated (i.e., richer) when viewed through translucent material such as glass or water. When visible light strikes a surface, some frequencies are reflected and others are transmitted. The reflected frequencies which match the absorption spectrum of the colorant in the substrate (such as paint or wood) create a colored reflection.
The wavelengths of light that an item reflects define its "color." This is governed by the arrangement of electrons in the atoms of that substance, which will absorb and re-emit photons of different energy in accordance with intricate quantum principles. The color of an object's surface can change depending on what angle you view it from; white objects look red or blue under certain conditions. A colored object's appearance is determined by the relative amounts of each of the three primary colors: red, green, and blue.
These are the only two ways in which color can be manifested in an object. A colored object cannot also be a material because materials are defined as being transparent to light. However, a colored object may still appear opaque because of other properties such as size, shape, and density. For example, a small colored dot on a white background appears black because we cannot see through it even though it is made of matter.
Colors are very important in science because they can be used to identify elements on the Periodic Table. They are also useful for describing flowers, fruits, and animals. Colors are also used in chemistry to detect substances that react with each other. For example, if you mix vinegar and baking soda and let them sit for a while, the vinegar will turn into bubbles because there is no longer any sodium acetate left.