Many of the older tablet computers like the Apple Newton and Palm PDAs used a pen, or stylus, as an interface. These offered features like handwriting and gesture recognition. But with the advanced touch screen features available today, is a tablet pen still necessary?
In some applications, having a pen can be extremely helpful. Some apps allow you to take handwritten notes on your tablet, so a pen would be the best tool to use for that. In addition, a pen is extremely useful for drawing, sketching and other artistic applications.
Most tablets today require capacitative input -- meaning, some kind of electrical current must interact with the touch screen. That's why your fingers won't work if you're wearing gloves. Tablet pens have a magnetic charge with lets them be used on a touch screen. If your work (or fun) involves precision movements, a pen might be a great addition to your collection of accessories.