Thunderbolt

Thunderbolt is a type of connector on computers, developed by the companies Intel and Apple. Three things run simultaneously through a single cable: data, the image for a monitor, and power for charging. The plug is small, oval, and looks exactly like the widely used USB-C plug. Thunderbolt can be recognized by the small lightning bolt symbol next to the socket. What’s special is the speed: current versions manage 40 to 80 gigabits per second. For comparison: an entire high-resolution movie could be copied in a matter of seconds at that rate.

One cable instead of five

In the past, a laptop at a desk needed several cables. One for the monitor, one for the external hard drive, one for the power supply, plus mouse and keyboard. Thunderbolt bundles all of that together. You plug a single cable into the laptop and are connected to the entire workstation. Such hubs are called docking stations.

Thunderbolt is especially important for people who work with large files. Anyone editing video quickly moves several hundred gigabytes a day. Over a slow connection, the waiting would be unbearable. The port also plays a role in the AI world: training data is enormous and has to be shuffled back and forth between computers and hard drives.

A common misconception: not every USB-C port can do Thunderbolt. The plugs fit into each other, but the technology behind them differs. A cheap USB-C cable plugged into a Thunderbolt port will only transfer at the slower USB speed. This explains many disappointed users who wonder about sluggish data rates.

What happens inside the cable

Thunderbolt doesn’t simply transport data. It packs several different connections into one shared line. Among other things, it includes PCI Express, the fast pathway inside a computer that graphics cards and hard drives connect to. Added to that is DisplayPort, the signal for monitors. You can picture it like a highway with multiple lanes.

Because PCI Express is routed through as well, a connected device behaves almost as if it were sitting inside the computer itself. This is precisely why external graphics card enclosures work at all. You connect a large graphics card to a thin laptop, and the laptop uses it for gaming or computing.

This closeness to the inner workings has a downside. A malicious device on the Thunderbolt port could theoretically access memory directly. Modern operating systems therefore require confirmation before a new device is granted access. Even so, you shouldn’t blindly plug in unfamiliar cables or docking stations.

Thunderbolt in stores and in product announcements

Thunderbolt is most commonly encountered in higher-end notebooks. All MacBooks have it, and so do many Windows laptops. Technical spec sheets then list something like “2x Thunderbolt 4”. The number indicates the generation, with higher numbers meaning more speed and stricter minimum requirements.

The term regularly appears in product news whenever Intel introduces a new generation. Thunderbolt 5 was announced in 2023 and doubles the bandwidth compared to the fourth version. Such announcements are also of interest to investors, since Intel thereby controls a standard used by nearly the entire laptop industry.

In everyday life, the benefit shows up in small things. A student closes their laptop in the lecture hall, comes home, plugs in a cable, and keeps working on two large monitors. The laptop charges at the same time. That is exactly what the port was built for.