This talk is about the Android platform with over 3 Billion active devices - not even counting devices that are based on AOSP (the Android Open Source Project code) but are not officially Android. Providing security guarantees in such a massive and diverse ecosystem with multiple stakeholders is a major challenge. This keynote will present the main aspects of the security model, system architecture, and mitigations and safeguards developed over more than 10 years. Some of the early design decisions shaped the platform from the start and still form the foundation for its current security posture, while many additional safeguards were added over time. More recently, an academic consortium has started building a public transparency database for collecting measurements about the security status of devices, both from special device farms under laboratory settings and from in-the-field devices through crowd sourcing. Using such data to check for compliance with the Android platform security model and potentially ranking devices based on their security attributes is another interesting challenge. In this keynote, we will also present the current state of this database and ides for next steps.