What's This 'Internet' I Keep Hearing About? - Part Six - Getting The Message Across

Now that we are able to deliver messages the hard part is over. All we need to do is to put stuff in our messages in a certain way such that it makes sense at the other end.
Letters we send in the real world always have stuff in common - they are written on paper and in a language understood by both sender and receiver. I've discussed before how conventions are important for networks to operate, and this important concept remains true for our messages.

All parts of the Internet transfer messages written in things called 'Packets', and the layout and contents of those 'packets' are done according to the 'Internet Protocol' (IP). You don't need to know these terms, but you do need to know that these simple messages are error prone and simplistic.

You can think of 'packets' as the Internet equivalence of a sentence - for an ongoing conversation, there would be many of them sent in both directions of communication.
Reliable message transfer on the Internet is done via 'TCP'. IP is fundamental to the Internet, but TCP is not - there are in fact other 'protocols' that may be used that I won't be covering.