regex cheat sheet:
\b word boundary
\w alphanumeric
\d digit
\W not alphanumeric
\D not digit
\B not word boundary
\s space (blank, tab, etc...)
\S not space
[AEXa-c] match anyone letter=A,E or X or a,b,c
[^1-4] anything but 1,2,3 or 4
metacharacter: * + ? . ( ) [ ] { } \ / | ^ $
^word match word at start of line
word$ match word at end of line
the|this the OR this
th(e|is) is the same as above.