It's impossible to imagine a world without smartphones, with over 2.9 billion smartphone users in 2018 and an expected growth in the number of users each year. Developing compatible mobile apps is challenging due to the numerous device manufacturers and OS iterations, making compatibility testing crucial. There are two types of compatibility testing: forward compatibility testing, which involves future-proofing your app by testing on new devices and operating systems, and backward compatibility testing, which ensures that your app can run on older versions of devices and operating systems. Balancing device coverage is key to ensuring compatibility, as testing on too few devices risks not supporting all the devices users will be using. Software compatibility also needs to be managed, covering different operating systems and other apps running at the same time. Device emulators are commonly used for testing, but they have limitations compared to real device testing, which can provide clearer behaviors. The best approach is to use both emulators and real device testing in tandem. Various tools and techniques can help identify common compatibility issues, such as text and alignment problems, frames and tables not functioning correctly, CSS issues, view issues, and more. Instabug's In-App Feedback reporting tool provides a simple way for users to send feedback, with customizable report categories, annotated screenshots, screen recordings, and detailed technical data attached to each report.