A library that helps maintain backward compatibility for Android applications.
AppCompat is a support library designed for Android development that allows developers to use newer features on older Android versions. It enables developers to use Material Design components and other modern UI elements while still supporting devices running older Android versions. It provides various widgets and themes that mimic the look and feel of newer Android versions, making sure that users on older devices have access to a similar experience.
The library also includes features such as vector drawables and support for the action bar, which visibly improves the functionality of applications across different Android versions. Developers can use AppCompat to reduce fragmentation and improve app performance on a wider array of devices.