Actually, a tablet PC does not have any mouse for interaction and a small keyboard can be attached, but optional. A tablet PC screen is integrated with digitizers which are responsible for acknowledging any physical touch or digital pen interaction on the screen with the virtual information portrayed on it.

Passive digitizer

A touch screen based tablet PC uses passive digitizer either capacitive or resistive, only knows where the position of the stylus or finger is when the user presses it and causes the pointer on the screen to jump to the location of the press and instantly "click." It leads to lower accuracy and a higher rate of error—e.g. when the user's hand rests on the screen surface—which makes them less common in tablet PC's.

Active digitizer

In most tablet PC's, an active digitizer is used and can be installed behind the screen for maximum visibility. It has the ability to track the position of the pen when it is in proximity to the digitizer so that the user can “hover” over the screen. It facilitates the users to navigate through menus without accidentally activating an item. The advantage of using active digitizer is that only movement of the stylus affects the mouse pointer and discards other causes like your hand on the screen. Almost all the manufacturers install a protecting covering to avoid any unwanted damage to the LCD screen.

Electromagnetic resonation based tablets are troubled with “jitter” and when around the metal at the edges of the screen may change the properties of the reflected signal. Digitizer may not be able to maintain a totally accurate sense of the pen's position making it difficult for writing small characters.

In some digitizer technology a battery powered pen is used which actively transmits RF signals to be received by the tablet sensor. As a result, it consumes very less power of the tablet PC itself, but higher size and weight of the pen because of the battery. The main advantage is that the accuracy problems related to interference from metal at the edge of the screen are not an issue, but they usually suffer from the lack of support in many graphics applications.

Hybrid digitizer

The modern tablet PC's digitizers are a combination of both active pen and passive touch input. These digitizers are called hybrid digitizers which enables the user to use both touch screen based navigation as well as the accurate inputs from the stylus. Operating systems, like Windows Vista, support hybrid digitizers and differentiate between pen and touch input. Eg-Lenovo X60 Tablet PC.