A stain is a contamination on the surface of a material, such as textiles. Stains can occur in a variety of ways, and have a broad range of causes. Here, there are four main categories: Fatty stains (e.g. from cooking oil or cream), Protein-based stains (e.g. from blood or milk), bleachable stains (e.g. fruit juice, coffee, red wine, tea, mildew, mould, etc.) pigment-containing stains (e.g. pen, felt-tip pen, watercolour, lipstick, grease, soil, makeup etc.) In addition, there is also a category of special stains, such as rust and the so-called mixed stains, which consist of a combination of different stain types.