What Does KB, MB and GB Mean?

In Tuesday's article on What Size Flash Drive You Need, we discussed the different sizes a digital file could be and what their average is. Some files were measured in KB (kilobytes) while others were in MB (megabytes) and still otheres were in GB (gigabtes). This digital capacity measuring system can seem intimidating at first, but once the basics are understood, it's quite simple.

If you're already familiar with the metric system, you have a head start as that is where the prefixes for these measurements comes from. For example, kilometer and kilobyte. The metric system does things in multiples of 100's, but for technology, you'll see it used in multiples of 1,000. Brain hurt yet? Here's a simple breakdown:

• Kilobyte- 1,000 bytes
• Megabyte- 1,000 kilobytes
• Gigabyte- 1,000 megabytes

There are measurements above and below the three measurements given there, but these three will be the ones you primarily see in computers and technology today. Think you've got it? Here's where things get a bit messy; These measurements are really metric and aren't really multiples of 1,000. If you're familiar with how computers work on a basic level and use binary (click here if you aren't) you know you know that they count by 8's, this is called a byte, and therefor instead of a kilobyte being 1,000 bytes, it's actually 1,024 bytes. Will you need to know this? Not unless you want to show off, but it's still good to know and there are nerds out there that will correct you on it.

Practical Tip of the Day:
The 1000 vs 1024 difference doesn't make much an impact on a small scale, but as you start storing more and more data, the impact becomes more and more pronounced. Check out this helpful chart from Wikipedia for a quick reference.

If I Delete Something, Is It Gone Forever?

Most of us have heard that when you delete something from your computer it's "not really gone." Which inevitably leads to the question of "How do I make it really gone?" In order to really understand why deleting something doesn't obliterate it, you first need a quick primer on hard drives. If you haven't already read the article on How Do Computers Remember Things, click here to go over it- we'll be building on topics covered in there.

When a hard drive remembers something (aka "saves" it) it doesn't usually write it down in one spot on it's discs. It usually spreads it out and puts different parts in different spots, and creates a sort of mini table of contents so it can quickly find all the spots. It does this so if there's a small problem with one of the discs, it might affect a small part of a file and therefor keep it still usable, whereas if all the parts were together, the entire file would be broken.

When you delete something, it doesn't actually delete the different parts scattered about your drive. Instead, it deletes that table of contents file and thereby forgets it. Eventually the hard drive will put other files in that same space (remember, hard drives are magnetic so it can easily be rewritten), but until then, that part of the file is there as good as new. As time goes on, it becomes harder and harder to read part of a file that's been rewritten, much like if you wrote something on paper with a pencil, erased it, wrote something else over that spot, erased that, and so on. Each time it gets harder to read what was originally there.

There are ways to make things more permanently gone. For example, the Mac has an option called "Secure Empty Trash" that will first delete the parts of the file by re-writing over them seven times with random 1's and 0's (click here if you don't know why 1's and 0's) and then delete the table of contents file. There are similar things on Windows and other types of computers. If you use a method like this, it's highly unlikely that the file would ever be able to be found. (I never say never on these kinds of things!)

Practical Tip of the Day:
While it might be tempting to use one of those permanently delete options like Secure Empty Trash, you don't want to use it frivolously. Just like the paper beign written on and erased in the analogy, extra wear is put on the hard drive when you use these methods, and therefor slightly shortened the lifespan of your drive. My general rule of thumb for when to use this method is this: If this were a physical document, would you put it in the trash or shred it? If shred it, then use that method, otherwise, don't worry.

Limitless power with limited numbers

Yesterday I mentioned that computers all come down to crunching numbers. In a way, computers came into being by people not wanting to do math themselves. (I can totally appreciate this- my ability to do even basic math in my head goes down as the number of digits involved goes up!)

You probably already know that computers are electric; You have to plug them in for them to work. What they do with that electricity is amazing. Sparing you the the techno-babble for a second, the electricity goes into the different parts of the computer and causes teeny-tiny bits to become electrically charged. If something has a charge it is called a 1. Yes, simply a one. If something does NOT have a charge, it is a 0.

This is why when you see movies like the Matrix you see all these scrolling 1's and 0's on the screen. Yes, it's mostly to make it look cool, but they're trying to invoke a sense of computing on the most basic of levels. It is from this collection of ones and zeros that you are able to read this now. That we're able to watch funny baby videos on YouTube, or chat with old friends on Facebook or any number of things. Pretty amazing, huh?

Practical Tip of the Day: All websites have addresses- just like houses- and, just like a house, you need to know it's address to get to it. If I want to visit my friend Sarah, but don't know her address, what could I do? Well, I would look her up in the Whitepages! Website addresses are often able to be found in search engines. These use complex math to find the most popular pages that match what you search for, and give you the results. Google is one of the most popular search engines, but there are others like Bing and Yahoo.