Note that 'tera' now officially means 1012 even in the context of data processing. The prefixes kilo, mega, giga, tera, peta, exa, zetta, yotta always refer to powers of 10.

To refer to powers of 210 (powers of 1024), use the new binary prefixes kibi, mebi, gibi, tebi, pebi, and exbi. So

1 terabyte = 1 TB = 1012 bytes
1 tebibyte = 1 TiB = 10244 bytes

These new prefixes were created in December 1998 by the International Electrotechnical Commission: see the node prefixes for binary multiples for fuller explanation.

It is permissible to use 'terabyte' to mean tebibyte on a temporary basis until industry standards have shifted to the new terms.

The prefix 'tera' was originally adopted by the eleventh CGPM of the SI in 1960. It comes from the Greek for 'monster'.