You might think, like almost everyone else, that the @ (at sign) is a modern invention, a symbol specially created for email addresses. But its history goes back much further, rooted in Latin and used by Arab sailors centuries ago. Today it's one of the most used symbols worldwide, yet one of the least understood.
If you're reading this on a computer connected to the internet, you probably have an email address and use the @ symbol daily. However, most internet users ignore its true origin and meaning. It seems like a modern character, but it's actually an ancient symbol, used in the Middle Ages over 500 years ago.
An Arabic Origin and a Latin Ligature
Most historians agree that the word "arroba" comes from Arabic, specifically from the term "ar-roub", meaning "quarter" or "fourth part". But the symbol itself has a different root: it was born from the practice of medieval copyists transcribing Latin manuscripts by hand. These scribes joined the letters "a" and "d" to form the Latin preposition "ad" (to or toward), creating the "@" symbol. It makes perfect sense: if you had to copy hundreds of pages by hand, you'd look for shortcuts. The preposition "ad" appeared frequently, so replacing it with a single stroke was practical.
Over time, the at sign spread to other contexts, such as official Latin letters, where it was placed before the recipient's name. One of the oldest known documents with a printed @ dates to 1536: a letter from an Italian merchant in Seville to Rome, detailing the arrival of three ships from America loaded with treasures. It reads: "Thus, one @ of wine, which is 1/13 of a barrel, is worth 70 or 80 ducats..."
The At Sign as a Unit of Measure
In that context, the @ represented a unit of measurement used by Greeks and Romans: it equaled "a quarter of an amphora". But it wasn't fixed; its value varied by product. For example, an @ of oil was about 12.5 liters, while one of wine exceeded 16 liters. It was also used as a unit of mass: it represented a quarter of a quintal, which in Spain and Latin America equals 46.0093 kg. So an @ was roughly 11.5 kg. In Argentina, older folks in rural areas still talk about "quintals of wheat per hectare".
Despite that 1536 document, some historians, like Jorge Romance from Aragon, claim the @ was already in use in 1448, in a record of a wheat shipment from Castile to the Kingdom of Aragon.
The At Sign in the Age of the Typewriter
As time passed, the at sign fell out of use in most regions, except in the United States, where it was used in accounting to indicate unit price. For example, you might see "15 boxes @ $5 each", meaning the value of each box. In English, it's read as "at", which fits perfectly. So when the typewriter was invented in the late 19th century, the @ was included on its keyboard. Since computer keyboards evolved from those machines, the @ is still there.
The Leap to Email
The connection between @ and email is much more recent. Engineer Ray Tomlinson created email in 1971 and needed a symbol to identify addresses. He looked at the keyboard and chose the @. "It would have been easier to use brackets, parentheses, or even a comma, but those symbols were already used for other purposes, and of the symbols that were left free, the @ was the best," Tomlinson explained. "Another point in favor of this symbol is that translating as 'at' in English gave a sense of location," he added.
The first email address in history was tomlinson@bbn-tenexa, which can be interpreted as "Tomlinson at (@) the bbn-tenexa machine". Thus, a character invented by medieval scribes to simplify their work became the universal symbol for email. Isn't that amazing?
Source: Wikipedia - At sign
