/ expression /, i.e /[A-Z]+/g basic format
/ name\?\*\\/ escape special characters with backslashes
() group with parentheses
| logical OR
Character classes
\w word \d digit \s whitespace (tabs, line breaks)
\W NOT word \D NOT digit \S NOT whitespace
\t tabs, \n line breaks
. any character

^world start of the strings
world$ end of the string

[xyz] match any x, y, z
[^xyz] NOT x, y, z
[B-X] match any capital letters between B & X.

viki|maria match viki or maria
z{n} n occurrences
z* zero or multiple occurrences
z+ one or multiple occurrences
z{min, max} min/max occurrences
z? zero or one occurrences