~     Home directory
$     Denote a variable (as in $HOME or $USER)
&     Run a command in the background
;     Command termination
&&    Continue to the next command upon success (AND)
||    Continue to the next command upon failure (OR)
|     Use output of the first command as input for the next
'     Treat all contents as literal
"     Treat spaces as literal, but expand variables 
\     Treat the next character as literal
( )   Execute contents in a subshell
{ ;}  Execute in current shell (terminate with semi-colon)
[  ]  Test expression
(( )) Evaluate contents as a mathematical expression
[[ ]] Test expression, returning 0 or 1

>  Overwrite existing content
<  Overwrite existing content
>> Append to existing content
<< Append to existing content

?  Match exactly one of any character
*  Match zero or more of any character

[0-9]    Any digit
[a-z]    Any lowercase alpha
[A-Z]    Any uppercase alpha
[a-zA-Z] Any lowercase or uppercase alpha
[abc]    Only a, b, and c
[!a-z]   No lowercase alpha
[!1-3]   No 1, 2, or 3, but all other digits
[b-hot]  Lowercase b through h, and the letter o and the letter t
[A-M0-9] Uppercase alpha A through M, and any digit

\b     Backspace
\e     Escape
\f     Form feed (like a non-returning newline)
\n     Newline
\r     Carriage return
\t     Horizontal tab
\v     Vertical tab
\\     Backslash
\cH    Control-H
\uHHHH Unicode character of hexadecimal value HHHH
\NNN   8-bit character with octal value NNN