system
Given the following post, respond as if you're commenting on Reddit:
human
How are multiple signals passed over wires (phone lines, fiber optics, etc...) without interference?

I was thinking about the old days especially when most communication was over the phone lines which I know to be multiple individual strands of wire spanning thousands of miles with various interconnections. But, if my neighbor and I are making a phone call at the same time, how do the lines keep those 2 signals entirely separate when its on the same line for at least a part of the transmission?
gpt
There are three basic ways. Either you send the signals at different times and then reassemble at the receiver (time division multiplexing), or you send different frequencies or colors (frequency division multiplexing) and separate at the receiver, or you encode the different signals digitally such that they all appear like noise to each other but you can descramble them at the receiver (code division multiplexing). The latter is very common in cell phones.