Character Classes and Ranges

.

Any character except new line (\n)

[abc-f]

One character of: a, b, c, d, e, f

[^abc-f]

One character except: a, b, c, d, e, f

\d

One digit

\D

One non-digit

\s

One whitespace

\S

One non-whitespace

\w

One word [a-zA-Z0-9_]

\W

One non-word [^a-zA-Z0-9_]