Test Regular Expressions interactively and reference essential regex syntax rules, character classes, anchors, and quantifiers.
\d Any digit (0-9)
\w Word character (a-z, A-Z, 0-9, _)
\s Whitespace (space, tab, newline)
^ Start of string line
$ End of string line
\b Word boundary
* 0 or more times
+ 1 or more times
{n,m} Between n and m times