Colour has three main characteristics; Chromaticity (colour family) Luminescence (brightness) and saturation (purIty). You can assign all kinds of emotional values to colour, such as warmth or coldness, joy sadness or danger. That makes a colour personal, perhaps something you experience or interpret without being aware of it. We have given all the colours a name, such as red, light blue or green. To avoid confusion, producers of printing inks and paints invented a universal colour code.
When light hits an object, some of it is absorbed and some of it is reflected, depending on the material the object is made off. The light that is reflected off of the object is what we see as an objects colour.