[Tech notes] Android API levels

The following table specifies the API Level supported by each version of the Android platform:

Platform Version	API Level
Android 2.3	9
Android 2.2	8
Android 2.1	7
Android 2.0.1	6
Android 2.0	5
Android 1.6	4
Android 1.5	3
Android 1.1	2
Android 1.0	1

The API Level identifier serves a key role in ensuring the best possible experience for users and application developers:

• It lets the Android platform describe the maximum framework API revision that it supports
• It lets applications describe the framework API revision that they require
• It lets the system negotiate the installation of applications on the user's device, such that version-incompatible applications are not installed.

Applications can use a manifest element provided by the framework API — uses-sdk — to describe the minimum and maximum API Levels under which they are able to run, as well as the preferred API Level that they are designed to support.

Development Considerations

Application forward compatibility

Android applications are generally forward-compatible with new versions of the Android platform.

Because almost all changes to the framework API are additive, an Android application developed using any given version of the API (as specified by its API Level) is forward-compatible with later versions of the Android platform and higher API levels.

Application backward compatibility

Android applications are not necessarily backward compatible with versions of the Android platform older than the version against which they were compiled.

Reference