If you have ever wired up a microcontroller, you have typed something like Serial.begin(9600) without thinking twice about that number or its unit. That "9600" is a baud rate, and the word "baud" is not an acronym or a technical abbreviation. It is a surname. The unit is named after Jean-Maurice-Emile Baudot, a French telegraph engineer who, in 1870, invented one of the first practical digital character codes. More than a century and a half later, his name still appears in the setup line of nearly every embedded project on Earth.
Who was Emile Baudot?
Baudot was born in 1845 and worked for the French Telegraph Administration. In his era, sending text over a wire meant Morse code tapped out by hand, one operator per line, slow and prone to error. Baudot wanted something faster and more mechanical. Around 1870 he designed a system built on a 5-bit code: each letter, number, and punctuation mark was represented by a fixed pattern of five on-or-off signals. Five bits give 32 possible combinations, enough to cover the alphabet plus control functions when you use a couple of "shift" codes to switch between letters and figures.
His hardware was just as clever as his code. Operators used a five-key keyboard, pressing combinations with both hands to spell out characters. Baudot then multiplexed several operators onto a single telegraph line by giving each a rotating time slot, so one expensive wire could carry multiple messages at once. The French Telegraph Administration adopted his system in 1877, and versions of it spread across Europe and beyond. His 5-bit encoding, later refined into the International Telegraph Alphabet No. 2, was a direct ancestor of the ASCII that your firmware uses today.
From a name to a unit
Baudot's contribution was so foundational that engineers later named the unit of signaling speed after him. One baud equals one symbol, or signaling event, per second. In the simplest case, where each symbol carries a single bit, one baud equals one bit per second. That is why on a basic UART link running at 9600 baud, you are moving roughly 9600 bits per second.
It is worth being precise here, because baud and bits per second are often used interchangeably and they are not always the same thing. Baud measures how many symbols cross the wire each second. Bits per second measures how much actual data those symbols carry. When a modulation scheme packs multiple bits into each symbol, the bit rate climbs above the baud rate. For the plain, one-bit-per-symbol serial links common in embedded work, though, the two numbers line up, which is why we casually say "9600 baud" and "9600 bps" as if they mean the same thing.
Why this still matters in embedded and IoT
Open any datasheet for an ESP32, an Arduino, a Raspberry Pi Pico, or almost any sensor module, and you will find baud rates everywhere. UART links between a microcontroller and a GPS module, a fingerprint reader, or a debug console are all specified in baud. Common values like 9600, 57600, and 115200 are not random; they descend from a long line of standardized telegraph and modem speeds that trace back through Baudot's work.
Understanding the vocabulary is more than trivia. When two devices fail to talk, a baud-rate mismatch is one of the most common culprits: set one side to 9600 and the other to 115200 and you get nothing but garbage on the line. Knowing that baud is a symbol rate, not automatically a bit rate, helps you reason about timing budgets when you push a link fast or squeeze data through a noisy channel.
There is something fitting about a 19th-century telegraph engineer's name living on inside 21st-century connected devices. The physical layer has changed beyond recognition, from clattering electromechanical printers to silicon running at gigahertz, but the core idea of encoding characters as fixed patterns of bits and clocking them across a wire at an agreed rate is exactly what Baudot pioneered. Every connected sensor we build still rests on that foundation.
At Fluidwire we design IoT and embedded systems from silicon to cloud, and getting the fundamentals like serial timing right is where reliable products begin. If you are planning a connected device or debugging one that will not behave, get in touch or read more about what we do.
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