Feb 2, 2013

Bit or Byte

Here's an important difference I should've known by now: Bit vs. Byte. There are so many things about computers the average user won't ever need to know through the course of their dealings, but this is one as important as Miles Per Gallon. 

I've been measuring speeds on the smart phone with the use of SpeedTest.net, and the numbers that come back have been a bit deceiving. By now I, like many people, are accustom to hard drive measurements and how to calculate what I need based on how large images, videos, or other files are. It's natural, therefore, to think about internet speeds in terms of these same measurements. Because I often download these files, it is also natural to think about how fast I can do so-- how many seconds, for instance, does it take to download a 10 megabyte file? SpeedTest.net appears to have the answer: lets say I open the site, click "Begin Test" and after some calculating it tells me I get 1 Mbps. That's one mega..byte?...per...second? That was always my assumption, and from there I'd conclude 10 Mb over a 1 Mbps connection takes 10 seconds

Turns out that is wrong. If you bought a new car that advertised 30 MPG, but after 30 miles you had used almost 4 gallsons it would be pretty annoying, and that's essentially how I felt when I discovered:

Mbps= MegaBITS per second. I have a 10 MegaBYTE file and I'm downloading it at 1 MegaBITs per second. 

So that's annoying. What's the difference between a bit and a byte then? From WiseGeek:
A gigabit is a unit of measurement used in computers, equal to one billion bits of data. A bit is the smallest unit of data. It takes eight bits to form or store a single character of text. These 8-bit units are known as bytes.
We calculate hard drive space based on bytes because bytes are what we are interested in storing. To say a hard drive can store X amount of bits isn't as important to us as how many bytes because a eight thousand random bits aren't as important as 8 thousand bits organized into 1000 meaningful bytes. So while you can talk about anything in bits, it's only really useful to talk about bytes when it comes to hard drive space.

With connection speeds, however, we're interested bits because information is transmitted at that most basic form. An image is broken down into bits and transmitted over the internet where it is reconstituted into bytes on the other end. The transmission speed is calculated, then, by how fast we can send each bite.

Thankfully, that's about all there is to it. It means you have to do some basic math when you want to determine how long a file of X bytes will take to download over an X bits per second connection, but happily the computer will do this work for you in the background.

Where this distinction really matters is when you're shopping for an ISP.

Lets look at the top and bottom end of what's available. Google Fiber is advertised as a Gigabit service (that's 1,000 Mbps), and before this explanation you might have assumed you could download a one gigabyte video in one second. A file that is 3.5 gigabytes? That will only take three and a half seconds, right? No, it will actually take just over thirty seconds. No big deal, right? Well, if you have a much slower connection (like I do) at around 1.5 Mbps, then that same 3.5 Gigabyte file will take five and a half hours to download. Here's a nifty calculator so you can use to compare download rates on various connection speeds: Download Time Calculator

At a time when Megabytes have become Gigabytes and now Terabytes in consumer electronics, it can be difficult for someone who would rather focus on their work than computer terminology to get the service they need. The difference between 1.5 Mbps vs 100 Mbps makes a huge difference in productivity for anyone, and it's important that we be able to get the speeds we need to handle the workload.

There is a point, however, and I won't delve too much into it here, that speeds become so fast that it doesn't matter if you understand the difference between bytes and bits. If you have a gigabit service like Google Fiber and can download one gigabyte in nine seconds-- you really don't care all that much about file size. Your focus begins to be about quality, and that's the importance of super fast networks.