A Key Performance Indicator (KPI) is a measurable value that demonstrates how effectively an individual, team, or organization is achieving key business objectives. KPIs are used to evaluate success at reaching targets, guiding decision-making, and driving improvement. They can be financial, such as revenue growth, or non-financial, like customer satisfaction scores. Selecting the right KPIs is essential, as they should align with strategic goals and provide actionable insights for performance management.