Today, it is easy to talk to friends wherever they are. You can call, text, or send an e-mail. But in the 1800's a message could take weeks to arrive by a horse-drawn carriage. The invention of the telegraph allowed messages to be sent much faster.
In the 1830's, two people in Great Britain invented a telegraph. Their machine used 5 magnetic needles and electricity. It was used by railroad companies.
Telegraph machines were connected by wires. Tapping a switch on one machine made needles on another machine twitch. The pattern made by the needles spelled out a message.
Telegraphs were a huge invention but later got replaced by the telephones.