Bit                              Abbrivated : b

Un bit est la plus petite unité de donnée dans un ordinateur. Un bit a une seule valeur binaire , 0 ou 1.

Plain and simple : 1 bit is either 1 or 0

Nibble                         Abbrivated : ?

One nibble is four bits or half of an eight-bit byte.

Plain and simple : 1 nibble is 4 bit

Byte                            Abbrivated : B

A byte is a unit of information that is eight bits long. A byte is the unit most computers use to represent a character such as a letter, number, or typographic symbol (for example. "g", "5" or "?").

Plain and simple : 1 byte is 8 bits

Kilobit                         Abbrivated : Kb

One kilobit is 1.024 bits or 2 to the 10th power bits. A 28.8 Kbps modem is one that operates at 28.8 thousand bits (kilobits) per second(this is approximately 2.8 KB).

Plain and simple : 1 kilobit is 1024 bits

Kilobyte                       Abbrivated : KB

One kilobyte is 1.024 bytes or 2 to the 10th power bytes.

Plain and simple : 1 kilobyte is 1024 bytes

Megabyte                    Abbrivated : MB

One megabyte is 1.048.576 bytes or 2 to the 20th power bytes.

Plain and simple : 1 megabyte is 1.048.576 bytes

Gigabyte                     Abbrivated : GB

1.073.741.824 bytes or 2 to the 30th power bytes.

Plain and simple : 1 gigabyte is 1.073.741.824 bytes or 1024 megabyte.

Terabyte                     Abbrivated : TB

One terabyte is 1.099.511.627.776 bytes or 2 to the 40th power bytes.

Plain and simple : 1 terabyte is 1.099.511.627.776 bytes or 1024 gigabyte

Petabyte                     Abbrivated : PB

One Petabyte is 1.125.899.906.842.624 bytes or 2 to the 50th power bytes.
One petabyte is roughly the equivalent to 20 million four-drawer filing cabinets full of text.

Plain and simple : 1 petabyte is 1.125.899.906.842.624 bytes or 1024 terabyte

Exabyte                    Abbrivated : EB

One Exabyte is 1.152.921.504.606.846.976 bytes or 2 to the 60th power bytes.

Plain and simple : 1 exabyte is 1.152.921.504.606.846.976 bytes or 1024 Petabyte

Terms

Megabit                    Abbrivated : Mbit

One megabit is 1.048.576 bits or 2 to the 20th power bits.
It's commonly used for measuring the amount of data that is transferred in a second between two telecommunication points.

Plain and simple : 1 meganbit is 1.048.576 bits or 131.072 bytes or 0,125 megabytes.

Mbps

One Mbps is 1.000.000 bits per second. Mbps stand for "Millions of bits per second".

Plain and simple : 1 Mbps is 1.000.000 bits per second or 125.000 bytes/s.

Gbps

One Gbps is 1.000.000.000 bits or 10 to the 9th power bits. Gbps stand for "Billions of bits per second".

Plain and simple : 1 Gbps is 1.000.000.000 bits per second or 125.000.000 bytes/s