A tablet, or tablet PC, is a portable computer that uses a touchscreen as its primary input device. Most tablets are slightly smaller and weigh less than the average laptop. While some tablets include fold out keyboards, others, such as the Apple iPad and Motorola Xoom, only offer touchscreen input.
Early tablet touchscreens were designed to work with light pens, but most modern tablets support human touch input. Many tablets now support multitouch input, which allows you to perform gestures with multiple fingers, such as pinching an image to zoom out, or spreading your fingers apart to zoom in. Tablets without physical keyboards allow you to enter text using a pop-up keyboard that appears on the screen.
Since tablets do not use a traditional keyboard and mouse as their primary forms of input, the user interface of a tablet is different than a typical laptop. For example, instead of double-clicking to open a program, most applications open with a single tap. Instead of clicking on a scroll bar to scroll through a window, most tablet applications allow you to swipe up and down anywhere within a window to scroll through the content.
Since tablet PCs provide a different interface than traditional computers, they offer unique possibilities for graphics applications, games, and other programs. Because of their small form factor, they are extremely portable and can be easily stowed in a backpack or a briefcase. Still, because tablets lack a keyboard and mouse, some tasks such as typing documents and writing email messages, are more difficult on tablets than traditional computers. Therefore, tablets are generally seen as accessories to laptops and desktop computers rather than replacements.