.plist is short for Property List and it’s a file that’s automatically created with every Xcode project. This file stores configuration information for the application at runtime (when the app is running). The information is stored in a format called a key-value pair. Similar to a dictionary, the key is the property name and the value is the configuration.
For example, when we set the status bar as “light” in the general settings pane, a property is automatically created in the .plist with
key = Status bar style, value : String = UIStatusBarStyleLightContent.
Setting a property
Change reflected in plist
This way, when the app runs, it will look for the key Status bar style and know to use the “light” style to colour the status bar. Here's what Apple has to say about Property Lists in their documentation, if you're interested in getting an in-depth understanding, you can check it out here: