Bits, bytes and words

Computer memory consists of a large number of 'two-state devices' (flip-flops)- (think of them as switches), which can be 'On' or 'Off'.

If the switch is 'On' it is storing the digit 1.
If the switch is 'Off' it is storing the number 0.

...hence the binary system of numbers is used, which consists only of numbers containing 0s and 1s.

A bit (Binary digIT) is a 0 or a 1.
So 1011 is a 4-bit binary number.

8 bits = 1 byte

1024 bytes = 1 kilobyte (K)
1024 kilobytes = 1 megabyte (Mb)
1024 megabytes = 1 gigabyte (Gb)
1024 gigabytes = 1 terabyte (Tb)

All data (text, pictures, sounds, video clips etc) is stored as binary numbers.

A word is the number of bits that the CPU can handle at a time (usually 16, 32, 64 or 128)