If you use a Mac, perhaps you've been a bit confused on the changing technology of connecting the charger or other devices to ports on your Mac. It's called "Thunderbolt", and the following article helps to explain a confusing technology.
And for me, it's particularly aggravating because the connections on external hard drives, for example, don't keep up with the changing technology on a Mac. So, I -- and probably you -- have to go shopping for adaptors to connect this and that to our Mac, and especially so if we buy a new Mac.
JimHamm