Bits & Bytes

Everything you can see on your screen,you could'nt see them without the invention of bits.

What is a bit?

"Bit" is contraction for " diginary bit ".Indeed, a bit could have only 2 values : 0 or 1.
In the Boolean logic, the 0 corresponds to " No/False ", and the 1 to " Yes/True ".
In electronic,they respictively want to say " opened " and " closed ".
Finally, we can use this binary language in magnetic; 0: North , 1: South, and sometimes in optic; 0:black , 1:white.
I'm only going to tell you about the informatic ( boolean ) logic.
Just remeber a bit is a 0 or a 1.
There is in a byte (octet) 8 bits,so 8 digits. It allows to count to 255.


* Kilo- (k), thousand ;
* Méga (M), million ;
* Giga (G), billion ;
* Téra (T), thousand billions ;
* Péta (P), million billions ;
* Exa (E), billion billions.


Por example,a picture of 3 Mb ( or Mo ) is composed of 3 000 000 bytes,who are composed of 8 bits each one,that to say a total of 24 000 000 of 1 and 0 .
I let you imagine for a movie!

But i lied to you : a kb is not 1000 bytes,but 2^10 : 1024 bytes; a Mb is 2^20 : 1 048 576.



But commercials don't know that. This is why when they sale you an usb key of 4gb,there is approximatively 3,8 Gb. They think a kb is 1000 bytes,whereas we just have seen it's 1024.
For an example more eloquent , when you buy a Hard Drive of 1Tb,it contain juste 931gb : 69 Gb less that announced.