The number of *unique users who take a defined action within a product on a given day*. It is a key engagement metric used to measure the activity and growth of a product. ## Why DAU Matters - **Growth Indicator**: Helps track user engagement trends and product adoption over time. - **Benchmarking**: Allows comparison against competitors or internal targets. - **Operational Planning**: Helps estimate infrastructure, support, and operational costs based on active user load. - **Seasonality Insights**: Reveals fluctuations in user activity due to trends, holidays, or campaigns. ## Limitations of DAU - **Potential Vanity Metric**: DAU alone may not reflect actual business value if not tied to meaningful user actions ([[Vanity metrics- Misleading Indicators of Success]]). - **Definition Matters**: A broad or misleading definition (e.g., counting logins instead of meaningful engagement) can inflate numbers without providing useful insights. - **Lack of Retention Insight**: DAU does not inherently show user stickiness or long-term retention. ### Related [[Monthly Active Users (MAU)]]