Conversion

In GA4 a conversion is the count of a key event that flows into Google Ads reporting.

After the rename, "conversion" no longer describes what you see inside Analytics reports; it describes the metric GA4 sends to Google Ads. You mark a key event, link the accounts, and that key event's count shows up in Ads as a conversion for bidding and reporting.

You mark purchase as a key event and import it into Google Ads. Analytics calls it a key event; Google Ads calls the same count a conversion and feeds it into Smart Bidding.

One action, two names, depending on the tool. The exact same event is a "key event" in Analytics and a "conversion" in Google Ads. People assume these are two different metrics and end up double-counting. They are not.

Analytics says key event. Ads says conversion. Same number.