Caret ( ^ ) Matches the expression at the start of a line, as in ^A Question mark ( ? ) Matches the expression at the end of a line, as in A? Backslash ( \ ) Turns off the special meaning of the next character, as in \^ Brackets ( [] ) Matches any one of the enclosed characters, as in [aeiou] (Use a hyphen [ - ] for a range, as in [0-9] .) [^ ] Matches any one character except those enclosed in brackets, as in [^0-9] Period ( . ) Matches a single character of any value except end of line Asterisk ( * ) Matches zero or more of the preceding characters or expressions \{x,y\} Matches x to y occurrences of the preceding \{x\} Matches exactly x occurrences of the preceding \{x,\} Matches x or more oc...