A laptop computer, or simply laptop (also notebook computer or notebook), is small mobile computer, which usually weighs 2.2-18 pounds (1-6 kilograms), depending on size, materials, and other factors.
While teh 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 approxmate size of an A4 or letter size papersheet. The terms are imprecise: due to heat and other issues, many laptops are inappropriate for use on one's lap, and most notebooks are not the size of typical letter or A4 paper notebook.