This involves testing the app's features and functionalities to ensure they work correctly. Testers verify that user interactions, navigation, data input, and output functions are functioning as expected. They also test different scenarios and edge cases to uncover any defects or issues in the app's functionality.

App compatibility testing is performed to ensure that the app works seamlessly across various devices, operating systems (iOS, Android, etc.), and different versions of those operating systems. Testers check for any inconsistencies, layout issues, or functionality gaps that may arise due to platform differences.

Performance testing assesses how the app performs under different load conditions and usage scenarios. Testers evaluate factors such as app response time, resource usage, memory management, battery consumption, and network connectivity to identify any performance bottlenecks or issues that may affect the app's speed or responsiveness.

Security testing aims to identify vulnerabilities and ensure the app protects user data and maintains data integrity. Testers check for potential security risks, such as unauthorized access, data leakage, or insecure data storage. They also verify that the app adheres to security best practices and standards.

Usability testing focuses on evaluating the app's user interface (UI), user experience (UX), and overall usability. Testers assess the app's layout, navigation, visual design, ease of use, and intuitiveness. Feedback from real users is often collected to gain insights into how well the app meets their needs and expectations.

If the app is intended for a global audience, it is important to test its localization and internationalization aspects. Testers ensure that the app supports different languages, date and time formats, currencies, and cultural preferences, and that it adapts well to various regions and locales.

Regression testing involves retesting previously tested features and functionalities to ensure that changes or updates to the app do not introduce new defects or impact existing functionality. It helps ensure that the app remains stable and reliable throughout the development and release cycles.

UAT involves testing the app with real end-users or stakeholders to validate its functionality, usability, and overall suitability for their needs. It provides feedback on whether the app meets the desired requirements and meets the expectations of its target audience.

If the app is intended for distribution through app stores (such as the Apple App Store or Google Play Store), it must comply with the respective guidelines and requirements. Testers ensure that the app meets the necessary standards for submission, including app size limits, content restrictions, privacy policies, and other criteria.

Accessibility testing ensures that the app is accessible and usable by individuals with disabilities. Testers evaluate features such as screen reader compatibility, keyboard navigation, color contrast, and text size options to ensure compliance with accessibility standards, such as WCAG.