Key Event
Intermediate PronunciationEN/kiː ɪˈvɛnt/
A key event is an event the organisation treats as a valuable outcome; in GA4 the term is the official replacement for the word conversion.
In 2024 Google renamed conversion to key event inside GA4 and kept the word conversion for the outcomes exported to Google Ads and used there to optimise ad delivery. So a key events figure in a current GA4 report is what used to be labelled conversions, and comparing it against older reports without accounting for the rename is misleading. Outside GA4 a key event is simply an internal label: the team decides which few events count as success, and labelling too many events empties the label of meaning.
FAQ
Inside GA4 the two are effectively the same thing under a new name; conversion is now limited to the outcomes sent to Google Ads. Other tools still say conversion and rarely say key event, so when comparing two tools, map the names back to their definitions rather than to each other.
There is no fixed number and it depends on the business model: a store usually has one clear final outcome, while a SaaS product may count signup, activation and upgrade separately. The practical test is that each key event must change a decision; an event nobody acts on should not be one.