The slash ( / ), also known as the virgule, has several uses, most of which should be avoided in formal writing. Never use a backslash ( \ ) in place of a slash.
The one inarguably acceptable use of the slash in formal writing pertains to poetry. The slash, with one space on either side, indicates a line break.
In choosing your path in life, you might consider the words of Robert Frost, in his poem “The Road Not Taken”: “I took the one less traveled by, / And that has made all the difference.”
The slash sometimes serves as shorthand for per.
An $800/week salary.
A top speed of 250 km/h.
The slash sometimes serves as shorthand for and.
He is enrolling in the JD/MBA program at Harvard.
The slash sometimes serves as shorthand for or.
The use of “and/or,” as in the third example below, is often ambiguous and therefore best avoided. A possible rewrite: “The deficit reduction will be achieved by spending cuts or tax increases or both.”
Each guest must present his/her ticket prior to entry.
Once the new president is elected, he/she will have little time to waste.
The deficit reduction will be achieved by spending cuts and/or tax increases.
In place of the Latin preposition cum
The Latin preposition cum means “combined with,” “also used as,” or “along with being.” The slash is sometimes used to convey the same meaning.
He worked in his office-cum-dining room.
He worked in his office/dining room.
She felt burned out after working for fifteen years in Hollywood as a manager-cum-therapist.
She felt burned out after working for fifteen years in Hollywood as a manager/therapist.
Certain abbreviations are formed with a slash.
c/o (care of)
P/E ratio (price-to-earnings ratio)
The slash is used to separate the numerator from the denominator in fractions.
Conflict or connection
The slash is sometimes used to represent a conflict or connection between two things. As explained here, the en dash can perform the same role.
The Paris/London train leaves in an hour.
This perfectly illustrates the nature/nurture debate.
The Paris–London train leaves in an hour.
This perfectly illustrates the nature–nurture debate.
The slash is sometimes used to indicate something spanning two years.
Everyone is still talking about the 1995/96 winter windstorm.
This audit covers only the 2005/6 fiscal year.