An Android developer is a software engineer who specializes in creating applications and software for the Android operating system, which is used on a variety of mobile devices such as smartphones, tablets, and smart TVs. Android developers play a crucial role in designing, developing, and maintaining applications that run on the Android platform.

Key responsibilities of an Android developer include:

1. Application Development: Writing code to create functional and visually appealing Android applications. This involves coding in languages like Java or Kotlin, and utilizing various libraries and frameworks provided by the Android SDK.
2. UI/UX Design: Collaborating with designers to implement user interfaces that are intuitive, responsive, and aesthetically pleasing. Android developers work with XML layout files to define the visual structure of the app.
3. Backend Integration: Connecting applications to backend services, databases, and APIs to fetch and update data. This often involves working with technologies like RESTful APIs, JSON/XML data formats, and database management systems.
4. Performance Optimization: Writing efficient code and employing best practices to ensure smooth performance of applications, even on devices with varying hardware capabilities.
5. Testing and Debugging: Conducting thorough testing of applications to identify and fix bugs, as well as ensuring compatibility with different Android versions and devices. This may involve unit testing, integration testing, and user acceptance testing.
6. Continuous Learning: Staying up-to-date with the latest developments in Android app development, including new tools, techniques, and platform updates. Keeping track of design guidelines and user experience trends is also important.
7. Version Control: Using version control systems like Git to manage code changes, collaborate with other developers, and maintain a history of code revisions.
8. Security and Privacy: Implementing security measures to protect user data and ensure that applications adhere to privacy standards and regulations.
9. Publishing and Deployment: Uploading applications to the Google Play Store or other app distribution platforms, ensuring that they meet the platform's requirements and guidelines.
10. Collaboration: Working closely with cross-functional teams including designers, product managers, and quality assurance testers to ensure that the final product meets both technical and business requirements.
11. Code Documentation: Writing clear and concise documentation for the codebase, making it easier for other developers to understand and maintain the code.
12. Troubleshooting and Support: Addressing user-reported issues and providing technical support for the applications in production.