Big numbers, Speed
Big numbers
We will need to deal with a lot of big numbers in computing, so you need to know how they work. To talk about large numbers of things, we add a prefix to the item. For example, if we want to talk about a thousand meters, we look at the prefix for thousand (kilo-) and add it to "meter" to make a "kilometer." The most common unit of information (more on that later) is the byte. A single byte is too small to deal with, though, so let's deal with a million bytes, or megabyte. That's a thousand kilobytes. Your laptop probably has about 2 gigabytes of RAM. That's 2 billion bytes! New HDDs and SSDs often have a terabyte or more of storage.
Speed
Now that you know about big numbers, we can talk about computer speeds. The first thing you need to know is that computers are really very simple. They can only do a few types of things - such as add, compare values, and move values from one memory location to another. However, they do these simple things EXTREMELY fast. To talk about computer speeds, we'll measure the number of things a computer can do in one second. The unit for this is called the Hertz, abbreviated Hz. We use Hertz to measure all kinds of things, so learn this by heart:
1 Hertz = one thing per second
Example: when you are resting, your heart beats about 60 times each minute, or once each second. That's a rate of 1 Hz. If you are walking around at recess, your heart may jump up to 120 beats per minute, or 2 Hz.
Computer speeds work the same way. Except that instead of dealing with Hertz, we usually have to use gigaHertz (GHz). Most current computers operate around 2 GHz. That's 2 billion things per second! Even when you consider that pressing your spacebar may require a dozen operations or more from your computer, that's really, really fast!
Bottlenecks
So why does your computer sometimes seem NOT so fast? Well, that means some part of it is slowing it down. Your computer can only go as fast as its slowest part. That part is known as the "bottleneck." Imagine a typical bottle, and you'll understand what this means - how much you can pour out depends almost entirely on the size of the neck of the bottle. Your computer's bottleneck in a particular case could be a slow hard drive, too little RAM, a slow processor, or a poor network connection. It's important to remember that increasing the speed of a component that is NOT a bottleneck won't increase the computer's speed at all.