Monthly Active Users (MAU) is a key metric used to measure the number of unique individuals who engage with a software application or digital service within a specific calendar month. It's a widely adopted indicator in the tech and digital space - especially for mobile apps, websites, and online platforms - to gauge user engagement, stickiness, and the overall health of a product. By tracking MAU over time, businesses can identify trends in user behavior, evaluate the impact of product updates or marketing campaigns, and make data-driven decisions to drive growth and retention.