Mégabyte

The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix mega is a multiplier of 1 000 000 (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes of information. This definition has been incorporated into the International System of Quantities. In the computer and information technology fields, other definitions have been used that arose for historical reasons of convenience. A common usage has been to designate one megabyte as 1 048 576 bytes (220 B), a quantity that conveniently expresses the binary architecture of digital computer memory. The standards bodies have deprecated this usage of the megabyte in favor of a new set of binary prefixes, in which this quantity is designated by the unit mebibyte (MiB). The unit megabyte is commonly used for 10002 (one million) bytes or 10242 bytes. The interpretation of using base 1024 originated as technical jargon for the byte multiples that needed to be expressed by the powers of 2 but lacked a convenient name. As 1024 (210) approximates 1000 (103), roughly corresponding to the SI prefix kilo-, it was a convenient term to denote the binary multiple. In 1998, the International Electrotechnical Commission (IEC) proposed standards for binary prefixes requiring the use of megabyte to denote 10002 bytes, and mebibyte to denote 10242 bytes. By the end of 2009, the IEC Standard had been adopted by the IEEE, EU, ISO and NIST. Nevertheless, the term megabyte continues to be widely used with different meanings. Base 10 1 MB = 1 000 000 bytes (= 10002 B = 106 B) is the definition following the rules of the International System of Units (SI), and the International Electrotechnical Commission (IEC). This definition is used in computer networking contexts and most storage media, particularly hard drives, flash-based storage, and DVDs, and is also consistent with the other uses of the SI prefix in computing, such as CPU clock speeds or measures of performance. The Mac OS X 10.