As soon as you launch an iPhone app it stays in the system memory and uses quite a large amount of resources, even when you go back to the home screen and open other applications. You may think it’s closed, but it’s actually not. The iPhone app will stay in the memory to be launched quickly for subsequent use. This is a design consideration but the downside can be that the unused application holds up system resources.

Quitting an app completely is a simple task and can help you speed up the performance of your iPhone, especially if you accidentally open an app or wish to close one you do not expect to use for some time.

To close an app, simple press and hold the Home button for about five seconds. Keep holding until you see the application closes. This will ensure the application is completely closed and will free up the iPhone’s memory.