History
The slash goes back to the days of ancient Rome. In the early modern period, in the Fraktur script, which was widespread through Europe in the Middle Ages, one slash (/) represented a comma, while two slashes (//) represented a dash. The two slashes eventually evolved into a sign similar to the equals sign (=), then being further simplified to a single dash or hyphen (–).
Read more about this topic: Slash (punctuation)