[com2kid]

Over a wire it sends pulses of electricity which you can see with an oscilloscope.

Heck there is a standard for tcp/ip over short wave if you want to hear the bytes being transmitted. More widespread, those of us familiar with dial up modems are also aware that network traffic can be carried as actual sound.

Or fiber optics where network traffic is flashes of light.

Or IR transmissions, use your phone camera and you can see data being sent over the air. Not tcp/up but physical blinking lights sending digital data.

[jameshart]

All of these are, actually, a long way removed from the ‘stream of octets’ which TCP delivers between applications.

All the Wikipedia actually means by ‘stream of octets’ is ‘sequence of numbers between 0 and 255’. TCP is a protocol concerned with sending a message encoded as a sequence of such numbers from one computer to another, over a packet-based network (i.e. one where it can only send limited bursts of information at a time); and it helps make sure that the original number sequence is able to be reassembled, in the right order, and makes sure that all the pieces have arrived.

The fact that people have tried to explain ‘octet’ concretely by pointing to RAM chips or flashes of light in a fiber really points to the fact that a lot of computer people just mentally gloss over a lot of the things that are virtualized at lower levels in the stack.

Yes, those are physical manifestations of ‘bits’. But not necessarily the ones TCP is concerned with.