Drawing shows a form that usually corresponds to that of a real object or concept. It is subjected to strict two-dimensionality and is normally monochrome, or with very few colours in different graduations. In Chinese and Japanese art, writing and drawing are considered to be the same and they constitute mankind's most noble form of artistic expression. The execution of a drawing is generally brief and spontaneous, which is why it is often associated with the previous stage to the execution of a more laborious work, such as a painting or a sculpture. It serves as a work tool, a sketch, study or reminder. It is the cheapest technique that exists and it can be done on numerous supports and with diverse materials. It can be done in sgraffito (a drawing scratched onto a hard surface), it can be printed or cover a surface. Charcoal, stylus and burins, all kinds of graphite and micas, pastel, sanguine, silverpoint, chalk, ink and so on can all be used to do drawings. The supports are also very varied, although today paper predominates: parchment, leather, small panels, slate, stone, cloth and many more. The first paper used in the West is thought to date back to the 12th century, and the technique was extended by the Arabs. The first paper factory was founded in 13th century Italy. Drawing was spread with the arrival of the printing press and from there it quickly passed to form part of the engraving and woodcut techniques that contributed to the massive presence of images in the modern world.