Emulators are software applications that mimic the interface of a particular mobile device, offering advantages such as rapid bug identification and cost-effectiveness. However, their performance may not match real devices, and they only exist for common types of devices. In contrast, testing with real devices provides insights into actual performance, network variability, and realistic user experiences, but requires purchasing multiple devices and incurring significant costs and maintenance. A balanced approach using both emulators and real devices can leverage the strengths of each, while addressing their limitations, to achieve high-quality mobile applications.