What?
A terabyte (derived from the prefix tera- and commonly abbreviated TB) is a measurement term for data storage capacity. The value of a terabyte based upon a decimal radix (base 10) is defined as one trillion (short scale) bytes, or 1000 gigabytes.
The number of bytes in a terabyte is sometimes stated to be approximately 1.0995 × 1012. This difference arises from a conflict between the long-standing tradition of using binary prefixes and base 2 for memory sizes, and the decimal (SI) standard adopted widely both within and outside of the computer industry. Standards organizations such as IEC, IEEE and ISO recommend to use the alternative term tebibyte (TiB) to signify the traditional measure of 10244 bytes, or 1024 gibibytes, leading to the following definitions:
According to the SI standard usage, a terabyte (TB) contains 1,000,000,000,000 bytes = 10004 or 1012 bytes.
According to binary arithmetic, a terabyte contains 1,099,511,627,776 bytes = 10244 or 240 bytes. Ambiguity can be avoided by using the term "tebibyte" when the binary meaning is intended.
The capacities of computer storage devices are typically advertised using their SI standard values, but the capacities reported by software operating systems uses the binary values.
An NTFS formatted terabyte hard disk or partition in Windows XP shows 931 gigabytes of free, usable storage space.
List of bytes:
Value SI
1000 k kilo-
2000 M mega-
3000 G giga-
4000 T tera-
5000 P peta-
6000 E exa-
7000 Z zetta-
8000 Y yotta
