• \d matches any digit, equivalent to [0-9]
• \D matches any character that’s not a digit, equivalent to [^0-9]
• \w matches any alphanumeric character (plus underscore), equivalent to [A-Za-z_0-9]
• \W matches any non-alphanumeric character, anything except [^A-Za-z_0-9]
• \s matches any whitespace character: spaces, tabs, newlines and Unicode spaces
• \S matches any character that’s not a whitespace
• \0 matches null
• \n matches a newline character
• \t matches a tab character
• \uXXXX matches a unicode character with code XXXX (requires the u flag)
• . matches any character that is not a newline char (e.g. \n) (unless you use the s flag, explained later on)
• [^] matches any character, including newline characters. It’s useful on multiline strings

Lessons in this unit: