Basic hardware components of a personal computer, including a monitor, a motherboard, a CPU, a RAM, two expansion cards, a power supply, an optical disc drive, a hard disk drive, a keyboard and a mouse Inside a custom-built computer: power supply at the bottom has its own cooling fan.

Accessories such as a keyboard and mouse may be essential in order to operate your computer. Others - such as headphones, cameras, graphics tablets and barcode readers - may be useful for specialist tasks or the facilitate certain ways of working.

The CPU runs everything. The Power Supply Unit powers everything. The hard drives and SSDs provide long terms memory storage. The RAM provides short term storage while running a program.