Regex Tester

.Any character except newline (without s flag) \d \w \sDigit, word char ([A-Za-z0-9_]), whitespace \D \W \SNegations of the above ^ $Start / end of input (per line with m) \b \BWord boundary / non-boundary [abc] [^abc]Character class / negated class a* a+ a?0+, 1+, 0 or 1 of a a{2,5}Between 2 and 5 of a (abc)Capturing group → backref $1 (?<name>abc)Named group → backref $<name> (?:abc)Non-capturing group (?=abc)Positive lookahead (?!abc)Negative lookahead (?<=abc)Positive lookbehind a|bAlternation \\Escape a literal metacharacter