Laptops are portable computers that can be used in different environments and include a screen, keyboard, trackpad or trackball, and battery to operate without being plugged in. Supercomputers rely on parallel processing and can model complex phenomena. Microcomputers include a central processing unit on a microchip, memory, bus system, and input/output ports housed in a motherboard. Mainframe computers are large systems employed by organizations for applications like data processing, resource planning, and financial transactions, and have evolved from room-sized to networked configurations.