What Is Morse Code? How It Works and Still Lives On

By: Mark Mancini  | 
Morse Code
Samuel Morse invented Morse code as a way to communicate via a series of dots and dashes. The above spells out Morse code in, well, Morse code. ©HowStuffWorks

Samual F. B. Morse was a successful businessman and a presidential portraitist. But above all else, he is best remembered for his eponymous Morse code. What is Morse code? An elegant system that revolutionized communications back in the 1800s.

Even in the heyday of Silicon Valley and social media, there's still a place for the well-worn Morse code today. Just ask the U.S. Navy. It's one of the languages cryptologic technicians learn while training at the Center for Information Dominance at Corry Station in Pensacola, Florida.


As the forerunner to email, texts and other near-instant messaging mediums, we think Morse code deserves a tip of the hat.

Who Was Samuel Morse?

Parts of Samuel Morse's backstory read like a tragic Hollywood screenplay.

He was born in Charlestown, Massachusetts, on April 27, 1791. A professional painter, Morse found himself working on a portrait of the Marquis de Lafayette in 1825. The job had taken him to Washington, D.C., where he received a devastating letter. According to the dispatch, his young wife had died back at their home in New Haven, Connecticut.


Worse, by the time Morse got this message, it was too late for him to return in time for her funeral. She was laid to rest without him. Such was the pace of most long-distance communications in those days.

Morse was one of the entrepreneurs leading the way for the future. He was one of the developers of the first telegraphs built in the 1830s. To call any lone scientist or inventor the "father" of this technical breakthrough, which changed how people could send messages, would be misleading. Morse was just one of the visionaries behind the telegraph's early development.

Despite his limited scientific background, Morse had a real passion for electricity. In 1837, he showcased a prototypical telegraph that he'd built at a public demonstration. Like all telegraphs, his sent out pulses of electric current via wire. The pulses would make their way into a receiver — and this is where Samuel Morse's famous code came into play.


The First Morse Code Transmission

Morse's telegraph couldn't transmit voices or written characters. Yet by capitalizing on those electric pulses, he devised a new way to send coded messages.

Documents show that the original Morse code was Morse's brainchild — despite rumors to the contrary. That said, he had a brilliant partner by the name of Alfred Vail, who helped him refine and expand the system. Under the code, every letter in the English language — along with most punctuation marks and each number from 0 through 9 — was given a unique, corresponding set of short and long pulses.


"Long" pulses came to be known as "dashes" while the short ones were called "dots." In this iteration of the code, not all dashes were created equal; some lasted longer than others. And the spaces between pulses varied widely (depending on the context).

Soon enough, Morse got to show off his electric cipher. In 1843, Congress handed him a $30,000 grant to build an experimental long-distance telegraph between Washington, D.C., and Baltimore, Maryland.

The moment of truth came on May 24, 1844. Sitting in the U.S. Capitol's Supreme Court chamber, Morse sent a coded message along to Vail, who was waiting in Baltimore at the other end of the line. Morse knew just what to say.

At the suggestion of a friend's daughter, he transmitted a quote from the biblical Book of Numbers: "What hath God wrought?"

Dits and Dahs

Made up of short and long tones, Morse code is still in use today. The short bursts are "dits" and the long ones are "dahs."

Morse code
Mezzo-soprano opera singer Ada Jones taps out Morse code messages from her kitchen table. Note the Morse key hanging on the wall.
Library of Congress


Morse Code Goes Global

Long-distance telegraph lines spread like wildfire over the next few decades. So did Samuel Morse's code. During the Civil War, President Abraham Lincoln used it to keep abreast of battlefield developments.

And speaking of Honest Abe, when Western Union completed the first transcontinental telegraph line in 1861, Lincoln received its first message — a dispatch sent all the way from San Francisco to D.C.


But as Morse code took hold in other countries, problems emerged. To address these, German telegraph inspector Friedrich Clemens Gerke simplified the system in 1848. Among other changes, he did away with the extra-long dashes and revised many of the individual number and letter codes.

After some additional tweaks were made, this new edition was dubbed "International Morse Code." Meanwhile, the original version was retroactively labeled "American Morse Code." Outside Civil War reenactments, the latter is all but extinct today.

Yet, International Morse code was in for a bright future, making its way across long distances.


Learning the Basics of Morse Code

In the international standard, a "dash" is three times longer than a "dot." On paper, "-" is the symbol for a dash while every "." represents a dot. "E" is a simple letter and shortest code; it consists of just one "." Other characters are a bit more intricate. For example, "-.-." means "C."

If you're dealing with a letter that features multiple dots and/or dashes, there should be a pause equivalent to the length of one dot in between those components. The pauses that separate entire letters are longer, equal to three dots. You should divide individual words by even longer pauses measuring seven dots long.


No Morse code phrase is more iconic than "SOS." A universally recognized distress signal, SOS was first adopted as such by German telegraphers in the year 1905. Why'd they pick this letter combo? Because in International Morse Code, "S" is three dots and "O" is three dashes. See, "dot-dot-dot-dash-dash-dash-dot-dot-dot" (...---...) is an easy sequence to remember — even when you're in grave peril.

Morse code alphabet
The Morse code alphabet has been in place since the late 19th century and is still used today, despite our digitally dominated communications.
Public Domain


Applications Past and Present

Although the invention of Morse Code came about because of the telegraph, people found other ways to use it. With the dawn of radiotelegraph machines in the 1890s, coded messages could travel via radio waves. Likewise, some purely visual media have long histories with the International Morse Code. Beginning in 1867, ships began using onboard blinker lights to flash signals at each other.

Then, there's the case of Jeremiah Denton, Jr., an American Navy pilot (and future senator) captured during the Vietnam War. In a forced appearance on North Vietnamese television, his captors coerced Denton into saying that he was faring well behind enemy lines. But his eyes told a different story. By blinking in sequence, he used Morse code to spell out the word "torture."


Later in the 20th century, the code was largely phased out. The U.S. Coast Guard hasn't used it in an official capacity since 1995, and modern ships are far more reliant on satellite communications systems. However, Uncle Sam's Navy still trains intelligence specialists to master the code.

Another group that's showing it some love is the International Morse Code Preservation Society — a coalition of amateur radio operators with thousands of members around the globe. So, while the golden age of dots and dashes may be over, Morse code's still hanging in there. No distress signal required.


Morse Code FAQs

What is Morse code?
Morse Code is a method of communication in which characters are sequenced in two different signal durations using dots and dashes. These codes are transmitted as electrical pulses of varied lengths. Samuel Morse and Alfred Vail invented it.
Is Morse code still used?
Morse Code usage still persists today. It is popular among amateur radio operators, and some also use it to send emergency signals.
How do you use Morse code?
Morse Code uses an alphabet made up of dots and dashes (for instance, the letter "S" is three dots and "O" is three dashes.) To use it, one must tap the combination of dots and dashes needed and pause for the correct gap duration. There are longer gaps between words than letters in a word. The duration of gaps and the number of dots and dashes used determines what words or numbers the person is trying to convey via Morse Code.
What is the Morse code machine called?
The telegraph was the machine first used to receive Morse code.
How do you read Morse code?
Morse Code comprises of two signals: dots and dashes. Learning to recognize these signals and the spaces between each dot and dash is imperative to learning Morse Code. The dots used are simple periods while the dashes are long horizontal lines that appear like hyphens.