A unit of computer memory or storage capacity equal to one trillion bytes. It is commonly abbreviated TB.
Because of irregularities in the definition and usage of the term “kilobyte”, the exact number of bytes identified as a terabyte may be either of the following:
1,000,000,000,000 bytes – 1000 to the 4th power or 10 to the 12th power
1,099,511,627,776 bytes – 1024 to the 4th power or 2 to the 40th power
Let’s put this figure into context. The average video store contains about 8 terabytes of video. The books in the United States Library of Congress contain about 20 terabytes of text in total.
Personal computers with 64-bit CPUs and operating systems are theoretically capable of accessing one terabyte of memory. 1TB hard drives are available, although their 2005 cost keeps them out of reach of most individual users.