Technically, ballpoint pens are related to rollerball pens and gel rollers. The barrels of all three types of pens are similar in design. The main difference lies in the inks used. In ballpoint pens, a rather viscous ink is applied to the paper through a ball (hence the name), which is usually made of ceramic or metal. When moving over the paper, the ball rolls and transports fresh ink from the shaft to the front again and again.
