It is the name of a measure of weight, which does not belong to the metric system. Colombia is the fourth part of a bundle. Fourth of a quintal. Equivalent to 25 pounds. At, in English: symbol used in systems to form directions electronics, is the link between the name of the user and the company that provides the service of transmission of the message (operator).
In the middle ages, weight unit (1/4 of quintal; 11, 5 kg); in 1971, Ray Tomlinson used the symbol "@" as "at" (in English "in") to separate the user name of the e-mail server. From Arabic 1575; 1604; 1585; 1576; 1593; (ar-rub, the rubac; "the quarter") with something from the latin ad ("to" or "envelope").
