Metacharacter Reference Chart

The following table lists each metacharacter, what it does, and links to where you can find out more about it.

Metacharacter	Meaning	More info
`\`	Escape or create metacharacter.	Metacharacters
`^`	Start of input, or start of line in multiline mode.	Positions
`\A`	Start of input.	Positions
`$`	End of input, or end of line in multiline mode.	Positions
`\z`	End of input.	Positions
`\Z`	End of input, before trailing newline.	Positions
`\b`	Word boundary, between word and non-word characters.	Positions
`\B`	Inverse of word boundary.	Positions
`(?=…)`	Lookahead, contains a regex expression.	Lookarounds
`(?!…)`	Negative lookahead, contains a regex expression.	Lookarounds
`(?<=…)`	Lookbehind, contains a limited-width regex expression.	Lookarounds
`(?<!…)`	Negative lookbehind, contains a limited-width regex expression.	Lookarounds
`\n`	Newline character.	Encoded Characters
`\r`	Carriage return character.	Encoded Characters
`\t`	Tab character.	Encoded Characters
`\x##`	ASCII encoded character, ## is hex digit from 00 to FF.	Encoded Characters
`\u####`	Unicode encoded character, #### is hex digit, from 0000 to FFFF.	Encoded Characters
`\0###`	Octal encoded character, ### is octal digit, from 000 to 377.	Encoded Characters
`[…]`	Character class, match any one char in class.	Character Classes
`[^…]`	Negative character class, match any one char not in class.	Character Classes
`\d`	Any single digit character.	Character Classes
`\w`	Any single word character.	Character Classes
`\s`	Any single whitespace character.	Character Classes
`\D`	Any single non-digit character.	Character Classes
`\W`	Any single non-word character.	Character Classes
`\S`	Any single non-whitespace character.	Character Classes
`\p{Xxxxx}`	POSIX character classes, Xxxxx is keyword.	POSIX Classes
`\P{Xxxxx}`	POSIX negative character classes, Xxxxx is keyword.	POSIX Classes
`\p{Xx}`	Unicode character classes, Xx is one or two letter code.	Unicode Classes
`\P{Xx}`	Unicode negative character classes, Xx is one or two letter code.	Unicode Classes
`{…}`	Greedy numeric quantifier, contains fixed number, minimum, or range.	Quantifiers
`{…}?`	Lazy numeric quantifier, contains fixed number, minimum, or range.	Quantifiers
`{…}+`	Possessive numeric quantifier, contains minimum, or range.	Quantifiers
`?`	Greedy optional quantifier (1 or 0).	Quantifiers
`??`	Lazy optional quantifier (0 or 1).	Quantifiers
`*`	Greedy non-required quantifier (as many as possible, zero required).	Quantifiers
`*?`	Lazy non-required quantifier (zero, or as few as possible).	Quantifiers
`*+`	Possessive non-required quantifier (as many as possible, zero required).	Quantifiers
`+`	Greedy required quantifier (as many as possible, one required).	Quantifiers
`+?`	Lazy required quantifier (at least one, as few as possible).	Quantifiers
`++`	Possessive required quantifier (as many as possible, one required).	Quantifiers
`(…)`	Capturing group, contains a regex expression.	Grouping
`(?:…)`	Non-capturing group, contains a regex expression.	Grouping
`(?>…)`	Atomic non-capturing group, contains a regex expression.	Grouping
`\1` to `\99`	Backreference to captured group	Backreferences
`\|`	Alternation	Alternation