(As of SDK 2.0.1)
The API levels 1.0 through 2.0.1 are versions of the framework with which you develop Android applications (see http://developer.android.com/guide/appendix/api-levels.html for more). They’re fairly backward compatible but not completely. These are also referred to by integer API numbers and sometimes names:
1 = version 1.0
2 = version 1.1
3 = version 1.5 (Cupcake)
4 = version [...]
