A tebibyte is a unit of data storage that equals 2 to the 40th power, or 1,099,511,627,776 bytes.
While a terabyte can be estimated as 10^12 or 1,000,000,000,000 bytes, a tebibyte is exactly 1,099,511,627,776 bytes. This is to avoid the ambiguity associated with the size of terabytes. A tebibyte is 1,024 gibibytes and precedes the pebibyte unit of measurement.
For a list of other units of measurements, view this Help Center article.