Sub-expression or capture group: (foo) Named capture group: (?<name>foo) Non-capturing group: (?:foo) Lookahead: (?=foo) For negative lookahead, change = to

Sub-expression or capture group: (foo) Named capture group: (?<name>foo) Non-capturing group: (?:foo) Lookahead: (?=foo) For negative lookahead, change = to !: (?!foo) For lookbehind, add <: (?<=foo) For negative lookbehind, change = to !: (?<!foo) (Not from memory, had to look everything up...)