Q: What's the difference between a custom event and a key event (conversion)?

Q: What's the difference between a custom event and a key event (conversion)?

A: One is a measurement, the other is a label you put on it.

— A custom event is any action you track beyond automatic ones — fired via gtag, GTM, or built in Admin → Events → Create event.
— A key event (formerly 'conversion') is just a custom event you flagged as important: Admin → Events → toggle 'Mark as key event'.
— So every key event is an event, but not every event is a key event. Marking it changes nothing in collection — only how it's reported and sent to Ads.

TL;DR: Track first as an event, then promote the meaningful ones to key events with the toggle. Don't create separate 'conversion' events.

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