Digits and Word Characters

Character	Description
\d	Matches a digit character. Equivalent to [0-9].
\D	Matches a non-digit character. Equivalent to [^0-9].
\w	Matches any word character including underscore. Equivalent to A-Za-z0-9_].
\W	Matches any non-word character. Equivalent to [^A-Za-z0-9_].