Many pen-based software platforms have been introduced in the last decade, but only recently has the introduction of faster processors and hardware enabled mainstream introduction of tablet-sized pen-based PCs. This book tackles the challenge of writing compelling Tablet PC software on two fronts. First, it distills decades of usability research into pen-based computing to present an authoritative discussion of the optimal design of pen-based user interfaces. Second, it provides an in-depth exposition of the Tablet PC Ink SDK, complete with tips and tricks on how developers can produce the most powerful and natural "ink-aware" applications.