Definition: Thunderbolt

A peripheral interface from Intel introduced in 2011. First used on a MacBook Pro laptop, Thunderbolt provides simultaneous transfer of DisplayPort graphics for the monitor and PCI Express data for storage and other devices. Thunderbolt 3 added USB 3.1 Gen 2 connectivity.

Up to six peripherals can be connected in a daisy chain, providing an expansive external interface over one port. However, computers generally have several Thunderbolt ports. See DisplayPort, PCI Express and USB.

Thunderbolt 4
In 2020, Thunderbolt 4 is expected to have the same speed as Thunderbolt 3 but also support USB 4. Following are the Thunderbolt generations, and each is backward compatible with the previous one. See Thunderbolt Display and Thunderbolt Bridge.

          Data
 TB       Rate   ---Interfaces---   Port
 Gen     (GBps)  DP    PCIe   USB   Type

 1 (2011)  10   v1.1a  v2 x4        mDP
 2 (2013)  20   v1.2   v2 x4        mDP
 3 (2015)  40   v1.2   v3 x4  3.1   USB-C
 4 (2020)  40   v1.3   v3 x4  4     USB-C

Mini DisplayPort (mDP)

Thunderbolt 1 and 2 use the Mini DisplayPort plug and socket; however, Thunderbolt 3 switched to USB-C (see USB Type C).

Thunderbolt on a Desktop Mac

Two of the six Thunderbolt ports are used on this 2nd-generation Mac Pro. The black cable delivers DisplayPort to the monitor, and the orange cable transfers data between an external drive over PCI Express. See Mac Pro.