system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Millions of data signals are transmitted over the same cables simultaneously. How are they separated and "sorted" so they go to the right place?
gpt
The act of sending multiple messages on the same medium is called multiplexing. There are three distinct ways of doing it.

First is Time based multiplexing. Instead of sending everything at once, it all goes in a queue and gets processed one at a time. At a higher level, many protocols work like this.

Then we have frequency division multiplexing. This is where you send signals on the same wire at the same time using different frequencies. They can be read at the other end and separated back into the two distinct messages.

Then, in the world of fiber optics, we have angular division multiplexing. As the name suggests, this is where you send messages at different angles within the fibre optic cable. The reflection within the cable preserves the angle, and you can again read the distinct messages on the way out.