There is an old punctuation mark (some prefer to call it a symbol) popularly known as the slash. Its most frequent uses are to separate alternatives (this/that) or to signify a simple fraction (1/2). Sometimes it’s used to represent a line break, as when poetry is quoted in block paragraphs (“There was an old man from Japan / Whose limericks never would scan / etc.”), in which case the cognoscenti call it a virgule.
So basically, a slash is this: / a slash.
Simple name, slash. We’ve known it all our lives.
In the last few decades, we’ve begun to use a new, reversed version of the slash in various computing contexts (DEC, CP/M, and Windows use it to separate components of a file’s address on a storage device). This new kind of slash is backwards ( \ ) and is sometimes confused with a slash, because in isolation they are visually similar.
So the backslash is just this: \ a backward slash.
If you get confused, try writing a fraction: 1/2. It’s very hard to get it wrong with a fraction, because writing a fraction with a backslash looks and feels really weird. (Try it.) [Apologies to left-handers, though, since they may well find it is easier to write a backslash than a slash.]
That’s it, folks, just two words: slash and backslash.
Then, once upon a time, in a fit of frustration on a tech support call, some computer nerd yelled at his client, “No! For crissake you idiot! Use a FRONT slash, not a BACK slash! God! You people!”
And thus an innocent momentary attempt at emphasis was given life as a new word, for people who can’t remember that a slash is the one they’ve known all their lives, and a backslash is just a slash done backwards. For these folk, we now have the redundant and clumsy “frontslash,” which means precisely “slash.” Or, more polysyllabically, some prefer to call it a “forward slash.” Feel free to use either one whenever you’re feeling stupid, or talking to someone who is challenged by antonyms words. Just remember that although there are now four words (slash, frontslash, forwardslash, backslash), there are still only two things and the new words don’t eliminate any ambiguity or tell you when to use one or the other on a computer.
“Frontslash” and “forward slash” are a bit like saying, in the context of “forwards and backwards,” that the opposite of “backwards” is “frontbackwards” or perhaps “forbackwards.” [This isn’t a perfect parallel, however, since we don’t use “wards” to mean “forwards.”]
A more legitimate comparison might be to say the opposite of anti-matter is posi-matter, even though there’s already a better and less ambiguous word: matter.
So the question is, does all this matter? Of course it does.