What is a bit and a byte
Giga, tera: you hear these words whenever people talk about storage. But what exactly are they counting? Starting from a single bit, we'll uncover what these units really are.
One bit means just two things
The single bit we've been looking at shows only two things: 0 or 1, on or off.
That's enough for yes or no, but on its own it can't easily hold numbers or text.
Switch the bit below on and off and you'll see there are only two cases.
What one bit can hold.
So, as we saw before, bits have to be grouped together.
But how many per group?
Too few isn't enough and too many is wasteful, and this is where a handy number comes in.
Group eight and you get 256
Computers settled on grouping bits in eights.
Eight bits can show as many as 256 different patterns.
That's more than enough for English letters, digits, and symbols.
This group of eight is called 1 byte.
Switch on 8 bits to make 1 byte.
Why eight, of all numbers?
Because it was just right: enough to hold one character and neat to work with.
So the byte became the basic unit computers use to handle information.
1 byte holds one character
Think back to Lesson 3: every character has a number, and that number becomes 0s and 1s.
One English character fits in exactly 1 byte.
Pick a character below and you'll see it turn into eight 0s and 1s.
One character = 1 byte.
One character is 1 byte, so a word in English is a few bytes and an English sentence is a few dozen bytes.
That's how storage is counted.
The amount handled at once: the word
If the byte is the basic unit of information, a word is the amount a CPU processes in one go.
Just as people eat one spoonful at a time, a CPU takes a fixed-size bite.
Today's computers usually handle 8 bytes, or 64 bits, per bite.
The size of one bite (the word).
That's exactly what "64-bit computer" means.
It can handle 64 0s and 1s at once.
The bigger the bite, the more work it can get through in the same time.
Kilo, mega, giga, tera
Now let's move to the big units.
About 1000 bytes make 1 kilobyte (KB), and about 1000 of those make 1 megabyte (MB).
Each step is a thousand times bigger, and giga and tera are counting bytes too.
Units that climb a thousandfold.
So a "512-gigabyte laptop" can hold about 500 billion bytes, which is about 4 trillion 0s and 1s.
The story that started with a single switch in Lesson 1 has come this far.
Giga and tera are, in the end, ways of counting switches.