In measuring data transmission speed, a terabit is one trillion binary digit s, or 1,000,000,000,000 (that is, 10 12 ) bits. A terabit is used for measuring the amount of data that is transferred in a second between two telecommunication points or within network devices. For example, several companies are building a network switch that passes incoming packets through the device and out again at a terabits-per-second speed. Terabits per second is usually shortened to Tbps.
Although the bit is a unit of the binary number system, bits in data communications have historically been counted using the decimal number system. For example, 28.8 kilobits per second ( Kbps ) is 28,800 bits per second. Because of computer architecture and memory address boundaries, bytes are always some multiple or exponent of two.