Non-capturing groups

Every plain group quietly captures the text it matched, ready for reuse later. Often you only want the bundling - to apply a quantifier or hold an alternation - and have no use for the capture. `(?:...)` is a group that bundles but does NOT capture: same grouping power, no stored slot.

Two reasons to reach for it. It keeps your capture numbers clean: skip the throwaway group with (?:...) and the ones you DO care about stay $1, $2 in order instead of shifting every time you wrap something. And it signals intent - a reader sees (?:...) and knows "grouping only". The next lessons lean on numbered captures, so the habit pays off fast.

Functionally (?:ab)+ and (ab)+ match the same text - this playground checks the match, not the capture slots, so both pass the drill. The difference bites the moment you start numbering groups, which is the very next lesson.