What Does Tablet PC Mean?

A tablet PC is a portable PC that is a hybrid between a personal digital assistant (PDA) and notebook PC. Equipped with a touch screen interface, a tablet PC usually has a software application used to run a virtual keyboard. However, many tablet PCs support external keyboards.
Tablet PCs have built-in Web browsing capabilities, multiple connectivity options, capacitive touch screens and multimedia - including high definition (HD) support. Tablet PCs are also equipped with accelerometers, which allow users to view display screens in portrait or landscape mode.

Techopedia Explains Tablet PC

When measured diagonally, most tablet PC displays range between seven and 10 inches. Some models run on x86 central processing units (CPU), but many rely on Advanced RISC Machine (ARM) processors, which consume less power and facilitate extended battery life.

Available in the early 1990s, personal touch-sensitive devices - or PDAs - received limited market success. Although the tablet PC and PDA share a similar form factor, a PDA is much smaller with limited capabilities. PDAs also require a stylus for user input.
In 2010, tablet PCs exploded into the market with the introduction of the Apple iPad, which is lightweight, allows finger input and is more affordable than its tablet PC predecessors.