CPU - Central Processing Unit
The Central Processing Unit (CPU) is like the main brain of the whole computer. It processes all the information that you input into the computer and all the information that is outputted by the computer. There are two main manufacturers out there today that make CPUs for computers, Intel and AMD. Many people in the computer world choose sides, either Intel or AMD, and swear by their manufacturer of choice. It's really all just a matter of opinion though. One brand has never been truly proven better than the other brand.
Kind of like RAM (which you'll read about next), CPUs are rated at different capacities. The average computer today typically has a 2GHz, or higher, speed processor. The higher the GHz rating, the faster a processor can "process" information. Another thing you will see today is multiple "cores" in CPUs. You'll hear the terms dual-core and quad-core tossed around a lot when looking at computers. A core is basically a brain inside of the processor. So dual-core would mean the processor has two cores that can process information at the same time. The same thing goes for quad-core, it has four cores that can process information simultaneously.
CPUs are definitely an important factor when buying a new computer. You typically cannot upgrade your CPU, so you want to make sure you get one that will suit your needs right out of the box. Just look at the requirements for the software programs that you plan on using. Make sure that you get a computer with enough processing power to run the programs and you'll be just fine.
RAM - What exactly is it?
RAM stands for random access memory. RAM is also referred to as "computer memory." As you can see in the picture on the left, RAM is physical memory cards that are installed inside of a computer. RAM is a very important factor when looking at computers. Most software programs have minimum requirements when it comes to RAM, and although computers now-a-days have multiple Gigabytes (GB) of RAM, you could still run into the issue of not having enough RAM to run everything you want to be able to run.
RAM is memory that is accessed at random by computer programs. When you open a program up and run it, RAM is being used (along with the CPU) to run that program. A good metaphor I always use is this: Let's say that you have 1GB of RAM, we'll call this a student sized desk. There are only so many things you can lay out on a student sized desk before they start falling off. Think of computer programs like that; you can only open so many before your computer starts to freeze up and not operate properly. Now upgrade your RAM to 4GB, we'll say this is an executive sized desk. You now have the ability to lay out many more things on this desk without them falling off. Same idea applies to the computer programs; you can open up many more things without the computer freezing up on you. More RAM equals more power and more capabilities. The average computer today comes with 4GB or more of RAM.
Hard Drives - The component that "knows it all"
The hard drive is the part of the computer that stores all of your information. Any information that you have on the computer is saved to the hard drive. All your documents, videos, pictures, music, programs, and even your operating system (Windows) are stored on the hard drive.
The hard drive is also rated in gigabytes like RAM is. The average hard drive capacity today is 500GB and larger. Desktop computers today are coming out with 1TB (1 Terabyte = 1,024GB) hard drives. Now you might be thinking "why would I need that much space?" well the answer is pretty easy; the more multimedia we use today, the more storage space we need. A full-length movie is roughly about 2GB of storage space. If you load your computer up with a bunch of videos, music, and pictures, you'd be surprised how much space you'd actually fill up.
When looking at new computers, you need to think about what you will use the computer for, because this will determine how much storage space you actually need. If you're buying a computer just to surf the web, check emails, and occasionally write a Word document, you won't need that much storage space at all. But if you plan on using your computer to edit videos and pictures, you'll want to get a computer with a large amount of hard drive space.