Simulators and emulators are tools used for testing mobile applications under different conditions. A simulator mimics the software environment but does not emulate hardware. Thus, it is suitable when the test objectives are focused on the application's internal behavior within the context of the software environment, not requiring an exact replica of the hardware conditions. This makes simulators particularly useful for scenarios where the primary concern is how the application runs in the software environment, rather than how it interacts with the underlying hardware.