Android has built-in tools and support which make it
easy for applications to do that, while at the same time
letting the system maintain control of what types of devices
application is available to. With a bit of forethought and
some minor changes in application's manifest file, it can
ensure that users whose devices can’t run application will
never see it in the Android Market, and will not get in
trouble by downloading it. This can explains how it can
control which devices have access to its applications, and
how to prepare its applications to make sure they reach the
right audience.