Understanding the 19th century telegraph system helps understand our current global internet.
I found "The Victorian Internet: The Remarkable Story of the Telegraph and the Nineteenth Century's On-Line Pioneers" a fascinating read, amazing what was done 150 years ago.
Here is a quote from the Wikipedia article:
The book describes to general readers how some of the uses of telegraph in commercial, military, and social communication were, in a sense, analogous to modern uses of the internet. A few rather unusual stories are related, about couples who fell in love and even married over the wires, criminals who were caught through the telegraph, and so on.
The culture which developed between telegraph operators also had some rather unexpected affinities with the modern Internet. Both cultures made or make use of complex text coding and abbreviated language slang, both required network security experts, and both attracted criminals who used the networks to commit fraud, hack private communications, and send unwanted messages.
We had e-commerce (code books for secure banking transaction via telegraph), hackers, and skilled technical workers with their own language and culture.
Telegraph operators even had their own equivalent to cell-phone text message abbreviations.