The CPU

• The central processing unit is often considered the brain of a computer system. Though it is just a small chip on the motherboard, it is responsible for making all calculations and coordinating the functions of the other internal components. CPU speed is measured in hertz, and examples include Microsoft's Intel series of processors.
  
  

The Memory Device

• The memory device of a computer system is responsible for storing running programs and executing requests made by the CPU. The capacity of a memory device is measured in bytes, and it consists of RAM chips affixed to a module on the motherboard.
  
  

Peripherals

• Peripherals make data input and output possible for a computer system. Examples include, but are not limited to, monitors, keyboards, mice, printers and speakers. Though a device can be considered a computer system without peripherals, most computer systems have one or more.