Backslash (\)

How to read it

Unicode names it REVERSE SOLIDUS (U+005C), with backslash as its other name; the ordinary slash is SOLIDUS (U+002F), also called slash, forward slash and virgule. The American Heritage Dictionary defines the backslash simply as “a backward virgule”. The forward slash is the one with jobs in ordinary writing: the dictionary lists separating alternatives (and/or), standing for “per” (miles/hour), dividing the parts of a web address and marking line breaks in quoted verse. Windows uses the backslash between the parts of a file path; Microsoft’s documentation calls it “the standard Windows separator” and says forward slashes in a Windows path are converted to it.

Also searched as: \, backslash meaning, backslash symbol, backslash vs forward slash.

Backslash or forward slash

The two lean in opposite directions. Web addresses use the forward slash (the American Heritage Dictionary’s example is whitehouse.gov/kids/patriotism/), and Windows file paths use the backslash. Unicode lists two mathematical look-alikes of the backslash, the set minus ∖ (U+2216) and the mathematical falling diagonal ⟍ (U+27CD).

The backslash in MATLAB

In MATLAB the backslash is the operator for solving a system of linear equations. Cleve Moler, who developed MATLAB, wrote in 2013 that every computer system he worked with in the 1970s had a backslash, which he put down to Bemer and the coming ASCII standard. He later learned that the German mathematician Kurt Hensel had used the same notation in a paper of 1928.