What is... Bits and Bytes

A guide to understanding bits and bytes

Author:  Paul Landers

It may all seem like computer jargon, and to some extent it is, however it is important to broadly understand the concepts of Bits and Bytes since the words KiloBytes, MegaBytes and GigaBytes will keep raising their heads in many aspects of computing.

Bits and Bytes can sometimes get complex and raise many discussions, however we're going to keep the concept as basic and as simple as possible.

Bit: A bit (short for Binary Digit) is the basic unit of information in computer technology. It only has one of two values - on or off. Your computer communicates in Bits - tiny electrical signals are passed around as either being signal on or signal off. The on/off signals are grouped together to form a sequence that is then interpreted as something meaningful. Picture two ships communicating via their semaphores - each sequence of light-on and light-off has a particular meaning. In computing terminology, each on signal and off signal is expressed as 1 and 0 respectively.

That's really as much as we need to understand about Bits. One of the few times you'll have to use your understanding of Bits is when trying to interpret the broadband/cable/satellite bandwidth you're being charged for by your Service Provider - bandwidth is generally measured in kilobits (Kb or Kbits) and megabits (Mb or Mbits) per second not KiloBytes (KB) and MegaBytes (MB) per second. We simply touched on it here because it introduces us to Bytes.

Byte: A Byte (sometimes said to be short for By Eight) is generally accepted to be a sequence of eight Bits. Bytes are the means by which humans manipulate the on/off sequences of Bits to become something meaningful in our language. For example, the capital letter A is expressed in binary form as 01000001, the capital letter B is expressed as 01000010, and so on. Notice the sequence of on/off (expressed as 1 and 0) that we discussed in Bits? So, every time you type the capital letter A, your computer interprets it as the sequence of  eight on/off signals above. Clever? I think so.

So, why a sequence of eight Bits to make a Byte? What's so special about eight? Why not  nine or ten? And, while we're questioning, why does eight and multiples of eight keep popping-up throughout computing technology?

Hey, enough with the questions! Give me a chance to answer and it will all fall into place (I hope).

Well, way back in computing's past, it was generally agreed (and I use the word loosely, very little in computing is ever agreed!) that each sequence of eight zeros (0) and ones (1) provides us with 256 possible unique combinations (multiply 2 x 2 eight times) and that 256 was the optimum number of combinations needed to cover our "character set" (alphabet, numbers, symbols etc). Simply put, each character we use can be expressed individually using a combination of eight 1's and 0's. Impressed? I thought so. You can now see the significance of eight. Since then, entire computer architectures have been built around that 8/256 Bit arrangement.

While a Byte signifies a unique and basic piece of "information" in computing technology, it also (for obvious reasons) signifies a basic unit of information "storage" in computing technology. All of the storage technology in your computer is measured and discussed in KiloBytes (KB), MegaBytes (MB, commonly called Meg/s) and GigaBytes (GB, commonly called Gig/s).

So, with all of the above in the back of your mind, here are the storage measurements generally used in computing. Everything tends to be 1024 because it provides the nearest whole multiple of the 8/256 arrangement:

• 1 KiloByte (KB) = 1024 Bytes
• 1 MegaByte (MB) = 1024 KiloBytes
• 1 GigaByte (GB) = 1024 MegaBytes

and for the sake of being complete:

• 1 TeraByte (TB) = 1024 GigaBytes
• 1 PetaByte (PB) = 1024 TeraBytes
• 1 ExaByte (EB) = 1024 PetaBytes
• 1 ZettaByte (ZB) = 1024 ExaBytes
• 1 YottaByte (YB) = 1024 ZettaBytes

Just when we had all absorbed the above, some storage manufacturers decided that they would revert back to the true decimal system to define storage measurement. So, in some manufacturers terms, kilo means 1000 (rather than 1024) and mega means 1,000,000 rather than 1,048,576 (1024 x 1024). Does it all really matter? Not really, unless you bought a new Hard Disk Drive that you believed was an 80 GB Drive and when you installed it, you system reported it as somewhat less than 80 GB. Now you know why. Read the details on the packaging so you know exactly what you're getting for your money.

Exaggerated of course but I'm sure you get the idea