The images.xcassets folder is called the Asset Catalog and was introduced with Xcode 5 as a way to manage all the images needed for your app, including app icons and launch images.
App Icons are graphical images that are used to indicate your app on the home screen of the iOS device your app is running on. When you create the icon for your app, you should be prepared to create it in a number of resolutions so that it looks great on different devices, and for various uses within the app as well. The icon is used for three places:
On the home screen, to give the user an easily recognizable image of your app.
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