\d: for digit\D: for non-digit\w: for word\W: for non-word\s: for whitespace\S: for non-whitespace.: for any character except newline^: for start of string$: for end of string[]: for a set of characters[^]: for a set of characters except the ones in the set|: for or(): for grouping*: for zero or more+: for one or more?: for zero or one{n}: for exactly n{n,}: for n or more{n,m}: for between n and m