Color activates the brain
Color is information and promotes communication

Our colorful world has always fascinated humans. Through millions of years of evolution, humans, animals and plants have developed sophisticated mechanisms to perceive and use colors.

"Colors are the smiles of nature" (J. Hunt)

However, do we all see the same thing?
There are, in fact, subtle variations. Let us consider a little test anybody can perform: accustom yourself in a dark room and open your eyes alternatively. In doing so, most people will realize one eye is more light-sensitive than the other. Moreover, it is not uncommon for one eye to perceive stronger colors in dim light conditions, whereas, the other one sees them somewhat fainter. It may also be that one eye views the world in a slightly reddish hue.

In view of such phenomena, the obvious question arises: If minor yet noticeable perception differences arise between the eyes of any given person, how great would such differences be between two unrelated individuals? The limited evidence our little experiment provides has also been demonstrated by cross-cultural studies at a much larger scale, e.g., the assignment of a certain color shade to color terms: for example, when is blue still blue, and when does it start to be purple? Where does yellow stop and orange or red start? Interestingly enough, these boundaries are drawn differently in different cultures. Even more so, there are languages that have no terms whatsoever to describe blue or green, which possibly indicates that these are not perceived as independent colors.
  
It is therefore essential to establish a valid and generally accepted definition of colors based on their physical properties.
In a nutshell, the physical cause underlying the color appearance of objects is the absorption and scattering of the contained colorants. Light absorption and scattering allow the reflection of only a portion of the light that reaches any given object. This portion, the spectral reflectance of an object, produces the so-called color stimulus. The spectral reflectance is measured to the extent in which a measured stimulus affects a standard observer is theoretically calculated.
For this purpose, there is a wide range of application-specific color measuring instruments, collectively referred to as spectrophotometers.

The use of spectrophotometers has significantly improved communication relating to colors and color variations between customers and suppliers.
As a result, the parameters for ensuring quality and internal control of color are greatly simplified, easier to document, and can be performed by anyone regardless of outside influences.