A laptop or notebook is a portable personal computer with a clamshell form factor, suitable for mobile use. Although originally there was a distinction between laptops and notebooks, the former being bigger and heavier than the latter, there is often no longer any difference. Laptops are commonly used in a variety of settings, such as at work, in education, and for personal multimedia. A laptop combines the components, inputs, outputs and capabilities of a desktop computer, including the display screen, speakers, a keyboard, and pointing devices (such as a touchpad or trackpad) into a single unit. The device can be powered either from a rechargeable battery or by mains electricity from an AC adapter.