The ancient Greek mathematician Thales of Miletus discovered around 600 BC that amber buttons that were rubbed with fur attracted light objects such as hair. The Greeks also discovered that if the amber was rubbed with the fur for a long time, an electric spark formed. We observe the same effect when we, for e.g. rub our hair with a balloon and see that the balloon attracts our hair. This effect is called the triboelectric (tribo is Greek for ‘rub’) effect. In 1733, the French chemist Charles François de Cisternay du Fay noted the existence of two types of charges and named them “vitreous” (Latin for glass) and “resinous” (from resin because it doesn’t look as clear as glass) because during that time electrical experiments were mostly conducted by rubbing glass rods with silk and attracting objects with it hence the glass rod possessed a “vitreous” charge and the object it attracted possessed a “resinous” charge; this would later be known as positive and negative charges respectively.