There is a history to this but as this is a tip I won't go over it.

If you like to read more into it see here *(external link)*.

In short, decimal prefixes are one's you are probably used to, where they're equal to 10^{3n} where n is a positive integer that increases by one for each prefix.

Binary prefixes, on the other hand are equal to 2^{10n}.

Binary prefixes are similar to decimal ones however their last two letters are replaced with "bi" (for example ki*lo*byte becomes ki*bi*byte).

Here's a table of some values to show the difference.

n | Decimal prefix | Decimal prefix value (10^{3n}) |
Binary prefix | Binary prefix value (2^{10n}) |
---|---|---|---|---|

1 | kilo (k) | 10^{3} (1000) |
kibi (ki) | 2^{10} (1024) |

2 | mega (M) | 10^{6} (1000000) |
mebi (Mi) | 2^{20} (1048576) |

3 | giga (G) | 10^{9} (1000000000) |
gibi (Gi) | 2^{30} (1073741824) |

4 | tera (T) | 10^{12} (1000000000000) |
tebi (Ti) | 2^{40} (1099511627776) |