What is hardware?

Hardware refers to the physical components that make a computer, namely:

Motherboard: this is the "brain" of the computer and joins everything else together, however it won't do very much by itself.
Power unit: this is the "heart" of the computer, distributing the power from the plug between the various components.
Computer Processing Unit (CPU): this does the "thinking" and calculating" to load and process information.
Random Access Memory (RAM): this is the computer's "short term" memory, remembering the information it is currently using and can be accessed quickly, such as files you are editing but haven't saved yet. When the computer switches off, the memory is lost.
Hard Drive: this is the computer's "long term" memory, storing all of your files such as music, videos and images.
Graphical Processing Unit (GPU): Similar to the CPU but focuses on calculations necessary for the graphics and screen to work. Sometimes the GPU is optional as the CPU can handle this task, but a GPU offers much better performance for videos, games and 3D software.
Peripherals: Any optional external attachments to the computer such as a monitor, mouse, keyboard and DVD drive. The computer itself can work without these when doing background tasks but will be inoperable to a person without them.