Google's Android Earthquake Alerts system is now operational globally, leveraging billions of Android smartphones as seismic sensors. The program detects earthquake shaking through phone accelerometers and sends early warnings to users in affected areas. This crowdsourced approach provides a potentially life-saving alert system, especially in regions with limited traditional seismic monitoring infrastructure. The system aims to provide seconds to minutes of warning, allowing individuals to take protective action before the arrival of strong ground motion. Privacy considerations are addressed through anonymized data collection and user control over participation.