Cohort analysis groups customers by a shared characteristic (usually signup date) and tracks their behavior over time. This reveals patterns that aggregate metrics hide. Why cohort analysis is powerful: - Shows if retention is improving or declining - Identifies product changes that impacted retention - Reveals seasonal patterns - Helps predict future churn Common cohort types: - Acquisition cohorts: Grouped by signup month - Behavioral cohorts: Grouped by actions taken - Value cohorts: Grouped by spending level A typical cohort chart shows retention percentage on the Y-axis and months since signup on the X-axis, with each row representing a different signup month.