Testing a mobile app is crucial due to the vast number of downloadable apps and device fragmentation. To develop apps, it's essential to test on as many devices as possible through mobile app testing. This involves understanding standard requirements such as usability, functionality, performance, edge cases, target devices, and other important elements. Testing stages include different life-cycle stages of an app, with manual and automated approaches used depending on the type of test. Manual testing is suitable for checkups, usability, edge cases, and performance, while automated testing is better suited for regression, end-to-end, and integration tests. A combination of both methods is often necessary to comprehensively test a mobile app, requiring a clear testing strategy and research on key devices in the target market.