About application on Android

Android has a growing selection of third party
applications, which can be acquired by users
either through an app store such as Google
Play or the Amazon Appstore , or by
downloading and installing the application's
APK file from a third-party site.[57] The Play
Store application allows users to browse,
download and update apps published by
Google and third-party developers, and is
pre-installed on devices that comply with
Google's compatibility requirements. [58] The
app filters the list of available applications to
those that are compatible with the user's
device, and developers may restrict their
applications to particular carriers or countries
for business reasons. [59] Purchases of
unwanted applications can be refunded
within 15 minutes of the time of download,
[60] and some carriers offer direct carrier
billing for Google Play application purchases,
where the cost of the application is added to
the user's monthly bill. [61] As of September
2012, there were more than 675,000 apps
available for Android, and the estimated
number of applications downloaded from the
Play Store was 25 billion. [62]
Applications are developed in the Java
language using the Android software
development kit (SDK). The SDK includes a
comprehensive set of development tools, [63]
including a debugger , software libraries , a
handset emulator based on QEMU ,
documentation, sample code, and tutorials.
The officially supported integrated
development environment (IDE) is Eclipse
using the Android Development Tools (ADT)
plugin. Other development tools are
available, including a Native Development Kit
for applications or extensions in C or C++,
Google App Inventor , a visual environment
for novice programmers, and various cross
platform mobile web applications
frameworks .
In order to work around limitations on
reaching Google services due to Internet
censorship in the People's Republic of China ,
Android devices sold in the PRC are generally
customized to use state approved services
instead.