🖊️ Ink flows from the refill through the tip tube to the ball, moistening one side of it. When writing, the ball rotates due to friction between the paper and the ball; the ink-moistened side of the ball ends up on the outside of the tube, and the ink is transferred from the ball to the paper.
The modern ballpoint pen was invented by Hungarian journalist László Bíró in 1931 and patented in 1938. In Argentina, where the journalist lived for many years, such pens are called “biro” in his honor. The English name for the ballpoint pen, “biro,” is also named after him.