Monthly Active Users

Monthly active users, or MAU, is the count of unique users who performed at least one qualifying action within a one-month window.

The load-bearing word is active, and its definition is a choice rather than an external fact: opening the app, signing in, or completing a meaningful action each produce a different number. The window also has two common readings, a calendar month and a rolling thirty days, and they never agree, so comparing two reports without aligning the window is meaningless. Most importantly the metric counts breadth, not depth: a user who came once counts the same as one who comes daily, so MAU can grow while real engagement falls. Summing daily active users never equals MAU either, because a returning user is counted only once across the month.