macbook thunderbolt
The Apple MacBook uses USB-C, a new connector set to replace USB. Thunderbolt 3 connects via the same connector, meaning one port can serve multiple purposes. Reuters

A small number of computers on the market are now sold with "Thunderbolt 3" support. It's a new supercharged connector that could transform computing. Here's what it's all about.

The key selling point is speed. Thunderbolt 1, which launched in 2011, was capable of 10 gigabits per second (Gbps). Thunderbolt 2, released in 2013, could achieve speeds of up to 20Gbps. Thunderbolt 3, which launched in 2015, can reach a staggering 40Gbps. The latest version of USB is only capable of 10Gbps.

That sounds like a lot of speed, and truth be told, most users won't need all that power. USB is cheap, fast and available almost everywhere, so Thunderbolt will find most value with serious professionals that need top performance.

The Razer Core is a good example of what Thunderbolt 3 can do: it's a bulky graphics processor designed to stay at a desk, so a user can plug in an ultra-thin laptop to get a performance boost without sacrificing portability. When the performance intensive work is done, the user unplugs and packs up.

The first two versions of Thunderbolt connected over mini DisplayPort, but while a Thunderbolt socket would accept mini DisplayPort peripherals, the reverse was not true. The same goes for Thunderbolt 3, which ditches mini DisplayPort for USB-C, a smaller, reversible connector intended to replace the ubiquitous USB.

The USB-C connector is thinner than the old socket, and that has helped Thunderbolt find its way onto tablets. The Dell XPS 12 is one of the first tablets to support Thunderbolt 3. It's also possible that Apple's new MacBook will later receive a Thunderbolt 3 upgrade. The current model supports USB-C, and the older MacBook Air supports Thunderbolt 2, so it may be possible Apple brings the pro connector onto its ultraportable.

Thunderbolt 3 also has other advantages. It uses the USB power delivery spec to provide up to 100 watts for charging, meaning no need for a separate charging port. It can also power monitors through DisplayPort technology: that extra bandwidth means it can power a 5K external display.

The connector also supports optical cables, capable of travelling longer distances. Intel first started developing Thunderbolt under the codename "Light Peak," developed with optical wiring in mind, instead of the copper usually found in USB cables. Ultimately, Intel also supported copper wires with Thunderbolt.

When Thunderbolt first launched most companies used copper because it was a lot cheaper and could also provide power. Optical cables do exist though for the serious pros, which are capable of connecting powered devices up to 100 meters away, compared to copper cables that can cover around 3 meters.