A telegraph is a device that sends messages across long distances using electrical signals transmitted through wires. Before telephones, computers, or radios, the telegraph was the fastest way to communicate over hundreds or thousands of miles. Instead of waiting weeks for a letter to arrive by ship or stagecoach, people could send a message by telegraph and receive a reply within hours.

The telegraph worked by sending patterns of electrical pulses through a wire. Operators used a special code called Morse code, where each letter was represented by a unique combination of short signals (called dots) and long signals (called dashes). An operator would tap out a message on a telegraph key, and another operator miles away would hear the clicks and decode them back into words.

Invented in the 1830s and 1840s, telegraphs transformed commerce, journalism, and warfare. Newspapers could report breaking news from distant cities the same day it happened. Businesses could coordinate shipments across the country. During the Civil War, President Lincoln used the telegraph to communicate with his generals on distant battlefields. By 1866, a telegraph cable stretched across the Atlantic Ocean, connecting America and Europe.

The telegraph remained essential for nearly a century until telephones and radios gradually replaced it. When you send an instant message today, you're doing something similar to what the telegraph did: sending information instantly across great distances, just with images and emojis instead of dots and dashes.