Graffiti is the handwriting recognition software used in PDAss based on the Palm OS. Graffiti also runs on the Pocket PC, where it's called "Block Recognizer".

The software is based primarily on upper-case characters that can be drawn blindly with a stylus on a touch-sensitive panel. Since the user typically cannot see the character as it is being drawn, complexities have been removed from four of the most difficult letters. 'A', 'F', 'K' and 'T' all are drawn without any need to match up a cross-stroke.

The Graffiti system has been the subject to a patent issue from Xerox, with its Unistrokes technology. Because of this, Palm has discontinued the use of the Graffiti system as it stood in further versions of its Palm OS software and instead licensed a variant of the Jot system from CIC, however the two systems are not identical.

For a chart of the Graffiti characters, see this link

For other definitions, see graffiti.