Usually a backslash (the one under the backspace key, not the one that shares a key with ”?") before a character that would usually be treated as a formatting instruction will stop it from being interpreted as such. Could be different for other machine-interpreted languages but when used this way, the backslash is called an "escape character".
I specified the location of the backslash as a way to tell the difference between that and the forward slash. Probably could have made my intent more clear if I'd stated that the slash sharing a key with the question mark was the forward one as you mention but didn't see a need.