A terabyte (TB) is a unit of measurement in computers and similar electronic devices. One terabyte holds 1000 gigabytes (GB) or a trillion (1,000,000,000,000) bytes, and 1000 terabytes make one petabyte.
Large organizations use terabytes of storage to hold massive amounts of data. People at home might use terabytes for backups. An external hard drive can be several terabytes.