The actual origin of the @ symbol remains an enigma.

@ History tells us that the @ symbol stemmed from the tired hands of themedieval monks. During the Middle Ages before the invention of printing presses, every letter of a word had to be painstakingly transcribed by hand for each copy of a published book. The monks that performed these long, tedious copying duties looked for ways to reduce the number of individual strokes per word for common words. Although the word "at" is quite short to begin with, it was a common enough word in texts and documents that medieval monks thought it would be quicker and easier to shorten the word "at" even more. As a result, the monks looped the "t" around the "a" and created it into a circle-eliminating two strokes of the pen.

Another story tells the @ symbol was used as an abbreviation for the word amphora. Amphora was the unit of measurement that determined the amount held by the large terra cotta jars that were used to ship grain, spices and wine. Giorgio Stabile, an Italian scholar, discovered the @ symbol in a letter written in 1536 by a Florentine trader named Francesco Lapi. It seems likely that some industrious trader saw the @ symbol in a book transcribed by monks using the symbol and appropriated it for use as the amphora abbreviation. This would also explain why it became common to use the symbol in relation to quantities of something.


Excerpts from atsymbol.com