Colours come from light interacting with eye light receptors. Colour is the visual attribute of objects. The study of colour is referred to as chromatics. This study includes the humans ability to see colour, the origin of colour in materials, colour theory and the physics of radiation in the human visible range.
Most light sources are mixtures of various wavelengths of light. Many sources can produce a spectral of colours as the eye cannot distinguish them from single wavelength sources. Most human colour perception can be created by mixing a combination of three colours called primaries. These colours are red, yellow, and blue.
| Colour | Wavelength interval | Frequency Interval |
| red | ~ 700-635 nm | ~ 430-480 THz |
| orange | ~ 635-590 nm | ~ 480-510 THz |
| yellow | ~ 590-560 nm | ~ 541-540 THz |
| green | ~ 560-490nm | ~ 540-610 THz |
| blue | ~ 490-450 nm | ~ 610-670 THz |
| purple | ~ 450-400 nm | ~ 670-750 THz |