The key components of a mobile application include a user interface (UI), backend server, and database. The UI is crucial for user interaction, focusing on design, navigation, and overall experience. The backend server manages data processing and application logic, while the database stores user data, preferences, and application content. Additionally, mobile applications may integrate with APIs for enhanced functionality and connect to third-party services, enabling features like push notifications and real-time updates. Security measures, such as encryption, are also vital.