A laptop is a type of computer that is small and portable, usually with a thin screen and keyboard. It typically runs on battery power and is designed for personal use. An ANALOG computer is an older type of computer that uses continuous physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. A desktop computer is a type of computer that is designed to fit on top of a desk and is typically used for home or office use. A microcomputer is a type of computer that is smaller than a desktop computer and is typically used for personal use. A NOTEBOOK is a type of laptop computer that is even smaller and more portable than a laptop. Finally, a mainframe is a type of large computer that is used by large organizations for critical applications, bulk data processing, and other tasks that require immense amounts of computing power.