\ escape prefix character
. "wildcard" – matches any character
+ quantifier: "one or more"
* quantifier: "zero or more"
^ beginning-of-line (except when used within a range)
$ end-of-line
? quantifier: "zero or one" (more about this in the next section)
| logical OR, among subpatterns within a group
[,] start-of-range and end-of-range
(,) start-of-group and end-of-group
{,} start, end of min/max quantifier
Reference