You can easily switch between the apps you’re using.
View open apps. Double-click the Home button to reveal your open apps in the app switcher. Swipe left or right to see more. To switch to another app, tap it.

Close an app. If an app isn’t working properly, you can force it to quit. Swipe the app up from the app switcher display. Then try opening the app again.
Search for apps. If you have lots of apps, you can use Search to find and open them. Swipe the center of the Home screen down to see the search field. See Search.