Gradle is a JVM-based build system that enables developers to write high-level scripts that can be used to automate the process of compilation and application production. It is a flexible plugin-based system, which allows you to automate various aspects of the build process; including compiling and signing a .jar, downloading and managing external dependencies, injecting fields into the AndroidManifest or utilising specific SDK versions.
apply plugin: The plugins which should been used normally just 'com.android.application' or 'com.android.library'.
android: The main configuration of your app
compileSdkVersion: The compile SDK versionbuildToolsVersion: The build tools versiondefaultConfig: The default settings which can been overwritten by flavors and build types
applicationId: The application id you use e.g. in the PlayStore mostly the same as your package nameminSdkVersion: The minimal required SDK versiontargetSdkVersion: The SDK version you compile against (should be always the newst one)versionCode: The internal version number which needs to be bigger on each updateversionName: The version number the user can see in the app details pagebuildTypes: See somewhere else (TODO)dependencies: The maven or local dependencies of your app
compile a single dependencytestCompile: a dependency for the unit or integration testsSee also
There is another tag where you can find more topics and examples about the use of gradle in Android.
http://www.riptutorial.com/topic/2092