The humble slash once did the job of the full stop and the comma
Medieval scribes used a slanting stroke called the virgule, Latin for little twig, to end sentences, mark pauses and break lines of verse. Over the centuries those duties drifted to the dot, the comma and other marks. The stroke survived by picking up new jobs, from fractions and dates to web addresses.
Its comma role lasted longest in France, where the virgule also flagged a word continuing onto the next line, a task the hyphen later took over. English names for the mark have shifted repeatedly. Eighteenth-century printers called it the oblique, which shortened to stroke, still the usual British term. Through the 1800s and into the early 1900s it was the shilling mark or solidus, because it separated shillings from pence in written sums. Slash is a latecomer, absent from Webster's dictionary until its third edition in 1961, and computing spread it widely.
Writing a fraction with a slash began as a way to squeeze the horizontal fraction bar onto a single line of type, with the earliest known examples coming from 18th-century England and Mexico. It even shaped the percent sign, which grew out of a horizontal form of zero over zero, itself a corruption of an Italian abbreviation for per cento. Using the slash for division followed, and in the mid-19th century the mathematician Augustus De Morgan urged it to save space on the printed page, noting that the division sign required lifting the pen too many times.
In everyday writing the slash usually stands in for or, as in Y/N, and since the late 20th century it has offered gender-neutral forms such as he/she. It can mark uncertain plurals like book/s or link stops on a route. Some style guides frown on it; Oxford's New Hart's Rules discourages the use that joins pairs like the Hemingway/Faulkner generation.
Most recently the word itself has escaped the page. People now say slash aloud to join two labels, as when a beekeeper talks about nectar slash honey, or to pivot mid-conversation to a follow-up question or a completely different topic.
Source: Slash (punctuation)
