Understanding of Appcompat_v7 in Android

1.APPCOMPAT_V7: Application Compatibility Pack, V7 says version 7, android2.1, this Compatibility Pack supports 2.1 versions of the system
2. Recently Google officially will be compatible with the jar package and some resource files alone to build an Android project, is actually a repository, right click on this project into build path-click on Android, you will find the is library ticked, indicating it is the vault. In fact, this library can be shared by multiple projects, the library already contains the V7.jar package, there are some compatibility resources, you can develop a number of projects, some of the common code, resources into the library, easy to use. The low version ADT does not generate the library automatically when the project is built, but when we need it, we can create a new project and hook the is library. The high-version ADT automatically generates the library, if not, just right-click on the Properties  -android-Library under your new project  and click Remove.
3. When your app is packaged or run, the library is automatically packaged and compiled as part of the project.

Understanding of Appcompat_v7 in Android