regex wildcards

. - a dot means “any character, any character at all”

* - an asterisk means “any number of the preceding character or class”. WARNING: zero is a number!

? - a question mark means “zero or one of the preceding character or class, but no more.”

+ - a plus sign means “one or more of the preceding character or class.”

[] - square brackets denote a class. For example [a-z,A-Z,0-9].

{} - curly brackets denote a range of repetition. For example, a{3-5} matches aaa, aaaa, and aaaaa.

() - parenthesis denote a grouping. For example, (group){1,2} matches group and groupgroup.