CPU (Central Processing Unit)
The brains of the whole PC. This is the section inside of your PC that does all the thinking, using complex mathematical sums.
This is the most important part of your computer set-up, and performs the majority of the complex tasks that you tell your computer to do.
Measured in GHz, the higher the number, the more powerful and faster your computer will be able to run.
Hard DiskIf the CPU is the brain, then the Hard Disk is the long term memory. Measured in Gigabytes (GB), the higher the GB the larger the available memory.
With most computers, the hard disk is easily changed, but requires you to open up your computer and can be quite daunting to the novice.
Memory (RAM)Random Access Memory, or RAM, is memory that can be accessed in any order. The computer uses it for short-term tasks while the computer is on, such as running programs. Once the computer is turned off, nothing is saved.
RAM is usually considered to be the primary memory of the computer, or primary storage. It is used to open and close applications, and displaying and manipulating data.
Because the RAM is used regularly, some of the more expensive RAM can have its own cooling system.
ModemUsually hidden away inside the computer these days, the modem allows you to access the internet.
A modem (also known by the more awkward name of modulator/demodulator), connects to a phone line allowing the user to access the internet.
Modems are becoming increasingly obsolete due to the more popular router.
MotherboardThe main circuit board of your computer. If the CPU is the brains, then this is the heart.
This is where you will usually find your CPU and RAM clipped to, and the type of CPU and RAM you can buy largely depends on the type of motherboard you have.
The motherboard can also be a deciding factor when buying a new graphics card too.
Power SupplyFound inside the computer, this device converts the power from a wall socket into a lower power that is suitable for the computer.
Because the computer requires a DC (direct current) rather than the wall socket standard AC (alternating current), a power supply is required. It can be external, but it is more common for it to be inside the case.
If your power supply fails, your computer won't work.