Tick options in SDK Manager

Run the SDK Manager

Tick the corresponding version of the SDK, from here you can basically know that an Android version corresponds to a version of the API.

Each of these packages has a few files:

Documentation for Android SDK: Android SDK documentation
SDK Platform:android SDK Kit, which must be installed
Samples for SDK:SDK Use example, you will see the corresponding file in the Adt-bundle-xxxx\sdk\samples directory after installation
Sources for Android sdk:sdk source code, in the installed Adt-bundle-windows-x86-20130522\sdk\sources directory will see the corresponding file
Google APIs: Google Maps provides a set of APIs, if your app does not use Google Maps, it can not be installed, but it is recommended to install
ARM EABI v7a System Image
Intel x86 Atom System Image
MIPS System Image
These three are the system impression files for simulators, which are under different CPU platforms. Must be installed, or the emulator will not open.

The corresponding file will be seen in the Adt-bundle-windows-x86-20130522\sdk\system-images directory after installation

Tick options in SDK Manager