Daily active users (DAU)

Daily active users counts the unique people who engage with a product on a given calendar day. "Engage" has to be defined by the team: opening the app, completing a core action, or something narrower, since a bare app open counts very differently from, say, sending a message.

DAU is one point on a family of active-user metrics that also includes weekly and monthly active users (WAU, MAU). Comparing DAU with MAU produces stickiness, a ratio that shows how often the average monthly user returns within a day. DAU on its own says nothing about depth of use, only reach, so teams pair it with engagement rate or session data to see whether daily visits are meaningful.

DAU matters because it is a fast-moving, easy-to-communicate signal of day-to-day health, and it is often the input to a north star metric. The common pitfalls are an inconsistent definition of "active" across teams, timezone boundaries that split a single user session across two calendar days, and inflation from bots or automated logins. Because DAU treats a thirty-second visit the same as a thirty-minute one, it should be read alongside retention analysis and cohort analysis rather than in isolation.