You've seen the word all over the Internet, it appears after search results all the time “cached”. You've heard people talk about it, and you even know that sometimes you have to clean out your cached items. (No, this doesn't mean have a garage sale.) But few people really know what “cache” really is and what it does on your computer.
Cache is pronounced just like “cash” but is far from the thing that comes in your paycheck. When you're dealing with a computer, a cache is just a collection of information that is stored in your computer of things that you use all the time so it is easier to pull them up when you want them. Basically – it's a cheat sheet for your computer. It simply holds information that you look at a lot by making a copy of it in the “cache” so that the CPU doesn't have to get the information from the main memory.
Caches have been found to be so effective in just about every area of computers since they can help to access the information in normal computer systems quickly and easily to make programs run faster. This is why when you pull up Brighthub.com, it comes up so fast because it is already cached in your computer (yes, yes, shameless plug).
Here is the tricky part – there are actually several different types of caches. Have no fear though – I'm only going to deal with the one that you will be most familiar with, which is the cache dealing with the Internet.
The Internet cache starts out with the BIND DNS daemon (and no, I didn't spell demon wrong). This little program maps out the domain names to IP addresses and stores them in it's little memory. Now, it's not that your computer cannot handle looking up your favorite web sites all the time, it is that with some of the unreliable networks, such as Ethernet LAN, there can sometimes be problems and gaps when it comes to pulling up pages quickly. So, your cache stores the pages that you visit frequently, like your home page, so that you will quickly have the page you want while it works to pull up the other pages around the Internet.
Your cache will have a ton of your frequently visited web sites that is managed in a web browser in your computer. This browser is used to help the server program, which is how all of the web requests are routed through your computer, so that it can easily get the information you are asking for quickly. Just about every Internet company out there uses a proxy cache to help save bandwidth for frequently used web pages, so it is not just your home computer that uses a cache to help it out.
While there is a lot more in-depth areas that deal with caches and what they do, this is a basic overview for what it is and how it helps your computer. Hopefully, you understand what the cache is on your computer now and you don't try to go out and spend it online.