The Design Support library adds support for various material design components and patterns for app developers to build upon, such as navigation drawers, floating action buttons (FAB), snackbars, and tabs.

What is an Android support library?

The Android Support Library package is a set of code libraries that provide backward-compatible versions of Android framework APIs as well as features that are only available through the library APIs. Each Support Library is backward-compatible to a specific Android API level.

What is Android support library and why is it recommended?

Originally a single binary library for apps, the Android Support Library has evolved into a suite of libraries for app development. Many of these libraries are now a strongly recommended, if not essential, part of app development.