Gallium nitride, or GaN, is a material that's starting to be used for semiconductors in chargers. It was used to make LEDs starting in the '90s, and it's also a popular material for solar cell arrays on satellites. The main thing about GaN when it comes to chargers is that it produces less heat. Less heat means components can be closer together, so a charger can be smaller than ever before—while maintaining all the power capabilities and safety standards.
Being lightweight and occupying less space makes GaN chargers great for travel. One charger is all most people will need when it has enough power for everything from a phone to a tablet or even a laptop.