Edit: This is for the standard US keyboard. A more general way of thinking about it, though a bit more to remember: associate "positive" with "forward", and see that '/' has a positive slope. Or just go listen to a BBC podcast, and let the sound of the broadcaster saying "bbc dot co dot uk forward-slash newspod" resonate in your head.
- "slash": the character you use in English and when typing fractions; and
- "backslash": the Microsoft-slash: backwards, like everything else they do.
Another way to remember is that (at least on US keyboards) the slash is always in the same place (on the same key as the question mark). The backslash, being the oddity that it is, is in different places, depending on the keyboard vendor.
"File slash" and "option slash" were far less confusing than decoding the secretary's concept of "forward" and "back."
Upslash / and downslash \ would make more sense, but this is what we have. My mnemonic is that forward and back are the opposite of what makes sense.
Perhaps a better way would be to think (for L-to-R language users) of the charater toppling "forwards" / or "backwards" \ WRT the text direction.
English is left-to-right. (And gravity is down.)
Is the slash "leaning forward" or is it "leaning backward".