When you buy a PC, you care about what it can do, how fast it can do it, and if it is worth the money. Usually it doesn't matter what is inside your computer — at least until you need to upgrade it later. If you've ever been curious about what goes on inside your computer's case, allow me to introduce you to our PC component friends.

I am going to assume that you have a desktop PC, since it is a good chance you have one. Laptops also have the same basic composition, but there are some special issues with them, so we'll cover  laptop innards in a later feature in this series. My point is to give you a tour of the computer system in very general terms so you can get an idea of what it takes to upgrade it and how to tell what you need to buy. Knowing what's under the hood at least a little bit can help you make the best decisions and get what you want out of your machine.

The Case is important, as a good design can maximize airflow — which helps keep your PC cool — and minimize noise. There are many kinds of cases, from the basic "something to hold it all in" case all the way to the "hide me the aliens are here" case with more lighting, cooling systems and gadgetry than you've ever seen.

The power supply is a critically important component because without it, nothing gets power. It is the central nervous system of the whole machine. The main differences in power supplies of the correct type are the wattage rating, and a bigger number means more power. You'll see 350W, 500W, and others. Contact your local tech head to verify how much is overkill if you're not sure exactly what you need.

The motherboard (mobo), also known as the mainboard, connects to the power supply via a large connector.  The mainboard is the biggest component in size in your PC, and the most important as well. It connects everything — expansion cards (like graphics cards for example) plug into it, the chip that controls your hard drive (called a controller) is on your mainboard, and much more. The type and composition of motherboard in your system determines its upgradability.

Wired to the main board are several things, including on-board Ethernet, video, modem (this is becoming optional), audio, memory sockets, processor socket, various connectors for USB, expansion cards, chipset, subsystems, and of course lots of circuits that link everything to everything else. In most cases, the on board features such as video and audio can be used just as they are when you sign on. These are limited to basic operation only, which is why you can't typically play serious video games on a system with on-board video; for graphics-intensive games you will need a graphics card or even two. In recent years PC makers have partly solved this issue by allowing the video subsystem to use shared memory with the main memory bank used by the PC for all its operations, allowing some increased functionality for video. You won't usually find serious audio hardware of any kind on most PCs, though mainboard manufacturers are typically including an HD audio chip, which can be useful with future upgrades. You can upgrade your video with a crazy insane graphics card, and add HD audio or surround sound to your PC via the expansion slots. Upgrade components are generally not all that pricey these days, but once again, what your mainboard will handle can be an issue if it is older or cheaper.

Optical drives (DVD, CD-ROM, BluRay, anything with a CD disc) are also connected to your main board via an extension cable. In older machines this will typically be a wide gray cable (there are other colors) known as IDE. Now, many drives, both optical and hard disks, use a newer connection called SATA, which looks like 2 thick-ish wires in red or blue most times, and has a much smaller connector than the wide gray IDE cables in older PCs. We will get into SATA, IDE, and some other connections later as a part of this series.

The processor is a component that is extremely important. It is the brains of the operation. All the evil plots are plotted there... Intel, is that you? Essentially, the processor makes decisions and routes information to its intended destination. The higher the number of Gigahertz — 1.8GHz, 2.0Ghz, 2.8GHz, and so on — the faster the processor. The speed of the processor also depends on the size of the Front Side Bus (think of it as determining how many lanes on your highway that information has to travel).

The RAM (random access memory) stores processed information, which is where currently running programs are held. It buffers what your processor is combing through at lightning speeds, which is why many times the biggest slow-down in your computer system is often the lack of memory, not your processor.

The Network Card (or NIC, network interface card) is what connects to the Internet or a local network. If you have a LAN at work, that computer also uses a LAN port on a network card. Many PCs have the network card and LAN port native on the main board, and it isn't technically a card anymore, but it used to be an add-in back in the day, so the nickname stuck. You can add a network card to your computer if needed, wireless or wired, via an expansion slot. They are quite affordable these days.

The expansion slots consist of a few types, made for different purposes. The most widely used is still the long-time mainstay called PCI, though there are newer slots replacing the PCI card slots post-haste. The new common slot type is called PCI-Express or PCI-E. It is the kid brother of traditional PCI, and much faster for the add-in cards you put in your desktop. AGP is another common expansion form factor, typically used by graphics cards.

Much like a fractal, the complexity of the inside of your computer increases as you zoom in and there is a wealth of information we can get into in detail in future parts to this series. For now, this is a basic starting point for the components you'll find inside your desktop PC.