. Any character\d Digit [0-9]\w Word char [a-zA-Z0-9_]\s Whitespace\b Word boundary^ Start of string/line$ End of string/line* 0 or more+ 1 or more? 0 or 1{n,m} n to m times[abc] Character class[^abc] Negated class(abc) Capture group(?:abc) Non-capture groupa|b Alternation(?=abc) Lookahead(?!abc) Neg. lookahead(?<=abc) Lookbehind(?<name>) Named group