A computer system in contemporary usage refers to a desktop system, including the computer itself (aka "The CPU" or "The Box") and all the peripheral devices needed to operate it, usually including:
The computer, usually mounted in a tower (vertical) case, including components: the CPU or central processing unit; a mother board or mainboard, including a BIOS; A graphics card; a sound card (often build onboard, ie. into the mainboard), a variety of disk ports to serve hard drives, disk drives and optical drives, a variety of peripheral ports, including USB ports, legacy serial and parallel ports, legacy psx, and SCSI; and LAN ports, either ethernet or firewire. A hard drive (sometimes more) is included for long-term data storage. The case also contains a transformer power supply and a number of fans to keep the internal components cool while operating.
A monitor, typically either a CRT or an LCD flatscreen.
A set of speakers to hear sound.
A keyboard, typically a standard 104-key QWERTY keyboard.
A mouse, typically a three button mouse with scroll wheel.
Schematic overview of the cardiovascular system.
Motion of the barycenter of the Solar System relative to the Sun
Ontario's electricity system four key components
DNA-Z computer model
Female Reproductive System (Illustrated)