Paint was originally formed as an egg tempera paint, where egg was used as the binder to stick the paint to a canvas, and pigment was added for colour – this was often plant extract. Nowadays, we have built on this principle and use polymers (long chains of carbon) as the binder, solvent (water or organic solvent), pigment (which are now in the form of chemicals which have a characteristic colour, or dyes) and certain additives which can improve the properties of the paint (make it shiney or matte, for example). Some paints, depending on their properties and the solvent we use to dissolve them, dry faster than others. I like to use watercolor when I am painting because you can easily fix mistakes with water and a ball of tissue because it is water soluble. For other paints like oil, you need to use white spirits which can be tricky to use correctly and can almost suffocate you with the fumes!