Ink and Strokes
The amount of pressure that a stylus applies to a screen is a critical factor in the realm of TabletPC computing. Unlike the typical mouse interaction, in which the parameters of "writing" are pixel location and pixel color, writing parameters in TabletPC are point location, color, and pressure exerted upon a given point. In TabletPC computing, when you make an uninterrupted line using a stylus, you have made a Stroke. All the Strokes that are made upon a surface are called the Ink.
The pressure exerted upon given points in a Stroke is a critical factor for the operating system when it comes to deciphering handwriting under TabletPC.