This sign is known to almost all Internet users. However, the symbol called "dog" appeared in the Middle Ages, and it had several meanings. It is now used as a delimiter in an email address.
The @ symbol was first mentioned in the 15th century, but it is possible that it was invented earlier. However, it is not yet clear how the @ symbol originated. According to one version, this sign was first used in writing by monks who wrote chronicles, including in Latin. Latin has the preposition "ad", and at that time the letter "d" was written with a small tail twisted upwards. And during a quick letter, the preposition looked like the @ sign.
Since the 15th century, the @ symbol has been used as a commercial symbol. So, he meant a measure of weight, about 12, 5 kg, the so-called amphora, and at that time the letter "A", which denoted the unit of measurement of mass, was decorated with curls and looked like today's @ sign.
There is a version that the symbol "dog" came from the word "arroba" - this is an old Spanish measure of weight, about fifteen kilograms, which the Portuguese, French and Spanish denoted in the letter with the @ sign, taken from the first letter of this word.
In the current commercial language, the name of the symbol "dog" - "commercial at" came from the accounts of the accounting department, which meant the preposition "on, in, on, to", and in Russian translation it looked like this - 6 pieces. $ 4 each (6 widgets @ $ 4 each). Since this sign was used in trade, it was placed on the keyboard of one of the first typewriters, and from there it moved to the computer keyboard.
Netizens owe the @ sign to their e-mail addresses to Tomlinson, who sent the very first e-mail back in 1971. In this case, the e-mail consisted of 2 parts - the name of the network user himself and the name of the computer device on which he is registered. In addition, Tomlinson preferred the @ (dog) sign on the keyboard as a separator between these parts, which could not introduce any confusion into the system.
In addition, in different countries this sign is called differently, but as a symbol "dog" it is known only in Russian. According to one of the versions - the sound of "at" in English is somewhat reminiscent of a dog barking, according to another - this symbol resembles a small dog curled up in a ball. There is another legend that the player had an assistant, his dog, who was looking for treasures, and also protected from terrible monsters. And this dog was designated by the @ symbol.