All the ports are both Thunderbolt 3 and USB-C
Think of the USB-C connector kind of like a duplex. It has a USB-side and a Thunderbolt 3-side. Thunderbolt 3 allows you to connect your Mac to displays, transfer data quickly between computers and hard drives; as well as, daisy chain external devices using just one connection. The new Macs have all these features available via the USB-C connector.
It's backwards compatible
For years, Macs have had USB and Thunderbolt ports. They were separate.
We used USB, to connect mouses, printers, displays and other peripherals to our computers. That type of USB is called USB-A. USB-C is backwards compatible and will support devices that use USB-A. So that's a plus.
Thunderbolt 3 is equally backwards compatible -- to Thunderbolt 2. The downside for connecting older USB or Thunderbolt devices is that you'll need an adapter to do so. That's because USB-C is physically a different port than USB-A or Thunderbolt 2.
No need to worry about plugging it in upside-down
How many times have you gone to plug in a USB cable and forgotten which side is up? Well, you won't have to do the USB flip dance any more. USB-C is reversible and there is no right side up!
It's super fast
Thunderbolt 3 allows for connection speeds up to 40 gigabits per second. While the new MacBook Pros have Thunderbolt 3, you might have peripherals (hard drives, keyboards, etc.) that don't use Thunderbolt. And that's okay.
With transfer speeds of up to 10 gigabits per second (USB 3.1 Gen 2), USB-C is pretty fast on it's own. This means if you're using a USB-C equipped external hard drive, that your files will still transfer pretty fast. And that's good news for all those photos and videos you're taking with your new iPhone 7 Plus.
It can do a lot
Thunderbolt 3 (USB-C) allows you to connect to monitors, charge your Mac, charge your phone from your Mac, transfer data -- all in one physical connector.
While the USB-C connector is undoubtedly the future path for connectivity, there lies an awkward transition ahead. This transition involves adapters and dongles to connect older devices that don't have a USB-C connector built-in. Though eventually over time, the convenience, power and versatility of USB-C will be widespread and everyone will be happy.
