So basically I am learning about how data is transferred through wires for a networking course and I stumbled upon this Ben Eaters video on this topic and I got a bit confused because I know that computers use 5 volts (DC) to communicate with for example a USB device and I also know that mains power is 110 or 220 volts (AC) at 50 or 60 Hz but when Ben explains how in his oscilloscope data is been transferred by detecting transition states in fluctuations of 1 to -1 volts I interpreted this as the 1v (DC) been turned into Alternating Current in order to send data. Is Alternating Current how every data communication is carried? How is it in USB? Can someone clarify what I'm saying here, please.
Also data could be transferred reading 5 and 0 volts, or 1 and 0 volts transitions and that couldn’t be called Alternating Current right?