Thunderbolt is a high-speed I/O technology developed by Intel that allows for bi-directional transfer of data at 10Gbps. It uses a single cable to support both DisplayPort and PCIe protocols. The Thunderbolt protocol has a physical layer that handles hot-plug detection and efficient data transfer with minimal overhead. It also has a transport layer that uses a switched fabric architecture to multiplex PCIe and DisplayPort traffic and support daisy-chaining of up to six devices on a single port.