8.
Every ballpoint pen is composed of three basic parts. The size, shape, and appearance of these parts may vary from pen to pen, but their function is always the same. First, there is the refill, the plastic or metal tube that holds the ink supply. Second, there is the barrel, which encloses and protects the refill. The third part is the point, the tiny metal ball that rotates in a socket. As it rotates, the ball picks up a thin film of ink from the refill and transfers it to the paper. The ink reaches the ball by gravity.