Ballpoint pens contain a free-flowing ink which is dispensed through a tiny rolling ball at the tip. As writing begins, the ball rolls with the hand motions, leaving a trail of ink behind. This design had been tried since the late 1800s, and had failed due to variations in ink thickness. However, the design was perfected, and ballpoint pens were first marketed in 1945.
Disposable pens feature standard ballpoint technology with one exception -- they are primarily composed of plastic for ease of disposal. These pens are manufactured to be used only until the ink is gone. Once the ink has run out, they cannot be refilled. Disposable pens are very inexpensive.
Refillable pens are made of a mixture of metal and plastic to ensure long life and durability. Pens are refilled by changing not only the ink reservoir, but also the ballpoint tip. Both the ink and the tip are joined together in one piece, making removal and refilling simple and tidy. These pens typically cost a little more than the plastic disposable variation.
Although some retractable pens are also disposable, the majority of retractable pens are refillable. These pens are designed not only to prevent ink from being dispersed on undesired surfaces, but also to prevent air and other elements from affecting the ink inside the pen. Retractable pens are one of the most commonly used types of ballpoint pens.
In addition to retractable, disposable and refillable, ballpoint pens are also available in a wide variety of vibrant colors and sizes. Pens may not only be purchased in standard blue or black ink, but are available in nearly any color in the spectrum. These pens may be sold in both standard and miniature sizes at office supply stores.