According to Fang Yihao Museum, signature pens refer to pens specially used for signature or sample signature, including water-based pens and oil-based pens. Pens used to be used, but now they are gradually replaced by gel pens, so these pens are collectively called signature pens. Water-based pens are generally used on paper. If they are used on a whiteboard or a sample, they are easily erased. Oily pens are generally used for sample signatures or other permanent marks, which are not easy to erase and can be cleaned with alcohol. Ballpoint pens can be divided into water-based pens and oil-based pens according to the different ink components used. The ink used in gel pens is between water-based and oil-based, also known as "gel pens".