system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How signals, be they cell phone signals or data through internet lines, are transmitted along their medium without becoming overwritten or scrambled by other signals also travel through the same medium.

If data is transmitted through pulses that designate 1's and 0's, how do you get multiple signals going through undersea cables or whatever without totally scrambling the data?

I feel like I'm completely misunderstanding how data transfer works.

EDIT: Thanks for the responses. lex418787 in particular. I think I understand cell towers now, but can anyone  explain the internet's system to me? I can see that different frequencies make sense for the cell's radio waves, but does the same apply to electricity?
gpt
There are two main ways.

One is called TDMA (Time-division multiple access).  In this scenario, everyone that's on a particular cell-tower takes turns transmitting data.  You might get 1-2ms, and then the next guy gets 1-2ms, and so on in a big circle.  The turns happen so frequently that you don't notice it happening.  Naturally, if you have too many people then the circle gets too big and people start to notice the degradation of quality.  So what really happens is the cell tower doesn't let too many people join the circle, the newcomers just get "Service Busy" or "Service Denied" on their phones.  GSM phones use TDMA (AT&T, T-mobile, etc.)

The other is called CDMA (Code-division multiple access).  In this scenario, each user gets an orthogonal code to use.  Think about an xy-graph.  You can move a dot in the X-direction (left & right) without affecting the Y-direction (up & down).  So, you could have 2 users, one person moves in the X-direction, and another moves in the Y-direction (kind of like the knobs on an etch-a-sketch).  Both people can send data at the same time without affecting each other.  In the real world, there are many many different codes, and the cell tower can differentiate between all of them.  Phones detect which codes are not in use, and when you make a call your phone uses an unused code.  However, there are still more phones than codes, so if too many people try to talk then they'll get the "Service Busy" message.  CDMA phones work on Verizon, Sprint, etc.