A terabyte (TB) is a measure of computer storage capacity that is 2 to the 40th power, or approximately a trillion bytes. A terabyte is more precisely defined as 1,024 gigabytes (GB). The prefix tera is derived from the Greek word for monster.
A 1 TB drive can hold the following:
According to futurist Ray Kurzweil in The Singularity is Near, the capacity of a human being's functional memory is estimated to be 1.25 terabytes.
The following chart illustrates some of the more common data storage measurements:
Hitachi began selling 1 TB hard disk drives (HDDs) to consumers in 2007. Prior to that, HDDs were relatively small and expensive. For example, when the IBM Personal Computer XT -- the successor to the original IBM PC -- was released in 1983, it was the first PC to include a built-in hard drive as a standard feature. At the time, HDDs were available in 10 megabyte (MB) or 20 MB capacities. It was not until 1991 that 1 GB disks were available to consumers, and even then a gigabyte of storage cost nearly $3,000.
The cost of a terabyte HDD
Like any other computer component, the cost of HDDs decreases over time. When 1 TB HDDs were first introduced in 2007, a consumer-grade drive cost approximately $375. Today, consumers can purchase a 4 TB external hard drive for approximately $150 (four times the capacity for less than half the cost). Eight terabyte drives are available for about $600, with some archive-grade drives priced as little as $300.