One name for each action
A shop’s app may record when a customer finishes buying; that recorded action is an event. If one team calls it checkout_complete and another Order Completed, an analytics report may miss some orders or count them twice. An event taxonomy gives the action one name and one meaning, such as Order Completed when the order is confirmed.
A tracking plan lists the agreed names, when each event should be recorded, and details to include, such as order value and currency.
Keep the meaning stable
Changing a name or when an event is recorded can make old and new reports hard to compare. Teams review and test changes, tell report owners, and stop collecting events they no longer need.