Learn about UI design aesthetics.
When Apple introduced the App Store in 2008, it created a revolution in the app industry. From that day on, anyone with a computer will be able to create and publish their app all over the world. In order to match the current default apps in iOS many designers mimic Apple’s skeuomorphic aesthetics and that became the standard for many years.
Apple wanted to create a similarity between the interaction of real life things and the iPhone apps. That was one of the reasons they decided to use skeuomorphism, and many designers followed the example. Example: The phone icon in apple emulates the phone receiver.