WITCH hack: Revision 2
\ "escape", "hack" (used to hack around, or escape, special characters.)
^ When used inside a regular expression
\ in front of any character will change it from a "metacharacter to a literal"<http://perlcabal.org/syn/S05.html#Simplified_lexical_parsing_of_patterns>, or "visa versa"<http://perlcabal.org/syn/S05.html#Backslash_reform>.
^ Other Uses
\ in front of whitespace creates an "unspace"<http://perlcabal.org/syn/S02.html#Whitespace_and_Comments> which is used to jam spaces in where they don't belong.
\o \c \x and \d used inside an interpolated string introduce "literal characters"<http://perlcabal.org/syn/S02.html#Literals>