A number system defines how we represent numbers. It defines which digits we can use, and what value each position (place value) in a number has.
The binary number system is the Base 2 Number System. It is a number system that only uses 2 digits (0 and 1).
The decimal number system is the Base 10 number system. It is a number system that only uses 10 digits (0 through 9).
The number base of a number system defines how many digits are in the number system, and the base of the exponent for each place value in a number.
The octal number system is the Base 8 number system. It is a number system that only uses 8 digits (0 through 7).
The hexadecimal number system is the Base 16 number system. It is a number system that only uses 16 digits (0 1 2 3 4 5 6 7 8 9 A B C D E F)
Bit means "binary digit". A bit is a single digit in a binary number. A bit can either be 0 or 1.
A byte is 8 bits.
A kilobyte (kB) is 2^10 bytes (1024 bytes) of binary data.
A megabyte (MB) is 2^20 bytes (1024 kB) of binary data.
A gigabyte (GB) is 2^30 bytes (1024 MB) of binary data.
