.
Any character except new line (\n)
(a|b)
a or b
(…)
Group
(?:…)
Passive (or non-capturing) group
[abc]
Range (a or b or c)
[^abc]
Not a or b or c
[a-z]
Lower case letter between a and z
[A-Z]
Upper case letter between A and Z
[0-7]
Digit between 0 and 7
\n
nth group/subpattern