A tablet personal computer or tablet PC is a tablet sized computer that also has the key features of a full size personal computer. A tablet PC is essentially a small laptop computer, equipped with a rotatable touchscreen as an additional input device, and running a standard PC operating system like Windows or Linux. The term was made popular with the Microsoft Tablet PC concept presented by Microsoft in 2001. Today, the term tablet is also used to refer to computer like devices operated primarily by a touch screen but not intended to run general PC operating systems or applications. Although tablet PCs are usually larger than tablet computers, they tend to be based on relatively small laptop designs, with screen sizes from 11 to 14 inches.

Tablet functionality is available in all editions of Windows 7 except the Starter edition. It introduces a new Math Input Panel that recognizes handwritten math expressions and formulas, and integrates with other programs. Windows 7 also significantly improved pen input and handwriting recognition by becoming faster, more accurate, and supportive of more languages, including East Asian writing systems. Personalized custom dictionaries help with the recognition of specialized vocabulary and text prediction speeds up the input process to make note taking faster. Multi touch technology is also available on some tablet PCs, enabling more advanced interaction using touch gestures with your fingers the same way a mouse is used.

A number of Linux based OS projects are dedicated to tablet PCs. Since all these are open source, they are freely available and can be run or ported to devices that conform to the tablet PC design. Maemo (rebranded MeeGo in 2010), a Debian Linux based graphical user environment, was developed for the Nokia Internet Tablet devices (770, N800, N810 & N900). It is currently in generation 5, and has a vast array of applications available in both official and user supported repositories. The Ubuntu Netbook Remix edition, as well as the Intel sponsored Moblin project, both have touchscreen support integrated into their user interfaces.

Google's Linux based Android operating system has been targeted by manufacturers for the tablet computer market following its success on smartphones due to its open nature and support for ARM systems, but some systems, like Toshiba's AC100 are more closely related to a tablet PC. There is talk of tablet support from Google coming to its web centric Chrome OS. Android 3.0 is the latest version of the android platform. It is optimized specifically for devices with larger screen sizes, mainly tablets, and has access to the android market. Android is the software stack for mobile devices that includes operating system, middleware and key applications.

Apple iPad and iPhone are not tablet PCs, they are tablet devices. As the iPad and iPhone use an embedded operating system, such as those found in PDAs and cell phones, they do not support full feature microcomputer operating systems. Before the introduction of the iPad, Axiotron introduced the Modbook, a heavily modified Apple MacBook, Mac OS X-based tablet computer at Macworld in 2007.