A KPI (Key Performance Indicator) is a quantifiable key performance indicator used to measure the effectiveness and success of a business or marketing action or strategy. It allows you to track results against specific objectives, providing data on aspects such as conversion rate, customer engagement, or return on investment. KPIs are selected according to the nature of the strategy and the objectives pursued, and are often grouped in a dashboard to facilitate monitoring, analysis, and decision-making. They play a vital role in optimizing performance and guiding future actions.