Definition: A terabit (Tb) is a unit of data storage equal to 1,000,000,000,000 bits. It's a large multiple of the bit and is used for extremely high-capacity data measurement.

History/origin: The terabit uses the SI prefix 'tera' to denote one trillion. Its use became relevant with the ever-increasing demands for data storage and transfer in the digital age.

Current use: Terabits are primarily used to measure the capacity of network backbones, high-speed data links, and large-scale data storage systems. They are also used in describing the aggregate bandwidth of communication networks.