A combination of the prefix “mebi,” which is defined by the IEC as 1,024 to the second power, and “byte.” Mebibyte is abbreviated “MiB.”
“Mebi” differs from “mega” in that the former is a binary prefix indicating a quantity of 1,048,576 units of data, while the later is 10 to the 6th power, or 1,000,000. Currently, “mega” is also popularly used to represent the binary quantity of 1,048,576, though the IEC and other standards bodies are trying to change this to reduce confusion in binary and decimal unit usages.