Tablet PC is pen-based computer, one that uses pattern-recognition software and facilitates it to accept handwriting as a form of input. It can be regarded as an evolution of the portable PC. It takes the best from a standard laptop, add some other features and encase them in a far smaller device. Thus it makes the idea of replacing the laptop with a powerful, chic gadget a reality.

Designed to operate more like a portable writing tablet than the traditional tablet-based computers, tablet PC includes handwriting recognition feature. It has also the ability to retain handwritten words and annotations without turning them into computer text. "Rich digital ink" as this ability is known is stored as a graphic after algorithms smooth out rough edges.

A stylus that may contain special electronic circuitry is used in a tablet PC to write on the computer display or on a separate tablet. Initially, these devices were limited to recognising geometric shapes for computer graphics applications and neatly printed alphabetic characters. But now the pattern recognition capability has been improved to the level where cursive input is acceptable, especially in personal digital assistants.

However, such input may not always be accurately interpreted by the software. Some software may require the use of a specially modified alphabet to enter data. In this connection, it may be mentioned that the integrated handwriting recognition in Windows XP Tablet PC Edition 2005 can recognise print, cursive, or mixed writing. Accuracy can be maintained by configuring the recogniser to expect left-handed writing or right-handed writing.

With the installation of a recogniser pack, recognition in a variety of languages can be ensured. The handwriting engine cannot be trained in Windows XP; but the integrated handwriting recognition in Windows Vista is trainable in a variety of ways. It has option for users to correct specific errors in recognition. Vista also offers the option to use personalised handwriting recognition. It can be used to see what words the user emails, or what words they must correct most often.