A laptop computer is a small mobile computer, which usually weighs 2.2-12 pounds (1-6 kilograms), depending on size, materials and other factors.
While the terms laptop and notebook are often used interchangeably, "laptop" is the older term, introduced in 1983 with the Gavilan SC. "Notebook computer" is a later coinage, which was used to differentiate smaller devices such as those of the NEC UltraLite and Compaq LTE series in 1989, which were, in contrast to previous laptops, the approximate size of an A4 paper sheet.
Laptops usually run on a single battery or from an external AC/DC adapter which can charge the battery while also supplying power to the computer itself.
As personal computers, laptops are capable of the same tasks as a desktop PC, although they are typically less powerful for the same price. They contain components that are similar to their desktop counterparts and perform the same functions, but are miniaturized and optimized for mobile use and efficient power consumption. Laptops usually have liquid crystal displays and most of them use different memory modules for their random access memory, for instance, SO-DIMM in lieu of the larger DIMMs. In addition to a built-in keyboard, they may utilize a touchpad or a pointing stick for input, though an external keyboard or mouse can usually be attached.
