Android/Introduction

Android speculations
Android's market penetration has extended through Android handset and tablet makers, some do also manufacture other consumer goods.

Stock Android
The most widespread flavors of Android are distributed in binary form in numerous smart-phones and tablet computers of companies that are members of the Open Handset Alliance (OHA), founded by Google, and which keeps tight control over 'first-launch' presentation of the operating system and additional software that is required for inclusion.

Because of Google's widespread services ecosystem that includes Google Drive, Google Maps, YouTube, and other Google properties, a hardware manufacturer intending to ship its devices with the Android operating system usually cannot avoid inclusion of built-in Google apps (part of Google Mobile Services) in order to successfully entice prospective buyers to purchase the device. Although Google apps can be separately installed by the user, it may be challenging to the average consumer (most people), who might then seek a competing device which does have the Google apps already installed.

Android trademarks and Google Mobile Services software can only be licensed by hardware manufacturers (OEM s) for devices that meet Google's compatibility standards contained within the Android Compatibility Definition Document. Following that path may also require that the manufacturer be a member of the OHA. Per OHA's rules, inclusion of Google Mobile Services is then mandatory, and the software bundle must be licensed from Google.

OHA members are not allowed to ship their devices with forks of the Android operating system, as doing so may terminate their membership in OHA, the license to use the Android trademark, and the right to pre-install Google apps.

Google Mobile Services is Google's proprietary application stack that includes Google apps, like the Google Play Store and assorted proprietary application programming interfaces (APIs). Many apps published in the Google Play Store directly depend on these proprietary APIs.

The operating system releases of these companies' devices are known as Stock Android.

To counter the mandatory nature of Google Mobile Services, large smartphone companies, like Samsung, almost always bundle their own software and services alongside Google apps that directly compete with Google's offerings, including even their own app stores. The pre-installed competing apps of manufacturers have variable quality, and smart-phone users often resent inclusion of such bundles, as they take up device resources that people wish to use for other purposes. This especially affects users of low-end devices with limited operating memory. In turn, larger mobile phone manufacturers release versions of their phones under the Google Edition label, which devices don't contain manufacturer bundles, but only Google apps.

Forks based on AOSP
There are other device manufacturers, such as Amazon and Nokia, who for various reasons do not want to use the Android flavor promoted by Google and the Open Handset Alliance. Some other manufacturers only market devices to countries where Google is blocked, so they can't use Google's Android by default.

These companies do peruse Android's open source code, but market the operating system under different names, have their own app stores, and develop their own APIs that seek feature parity with Google's APIs, which can be incompatible with one another.

Community forks
The open source community benefits from regular releases of Android source code, and creates community editions of Android which contain enhanced functionality not included or disabled in stock Android. One of the most popular community distributions is LineageOS.

The benefits of community editions:
 * More up-to-date software, as many manufacturers and mobile operators have a habit of not providing software updates to devices they distribute, especially for low-end devices. While some devices are too under-powered and thus incapable of running major new OS versions, then the more capable devices not offered updates by the manufacturer or operator are effectively orphaned.
 * There are also new versions of applications that don't work on older major versions of Android, as they require newer APIs; thus a major version upgrade extends the lifetime of a device's usefulness and reduces its obsolescence.
 * The forks are perceived to be cleaner, given that they don't contain manufacturer bundles, and on account of that take up less device resources. Neither are Google's apps included in these distributions, as said apps are proprietary, but they can be side-loaded or installed separately.
 * Newer versions are less buggy and are overall better-optimized.

Community distributions are not always fully functional on all phones, given that manufacturers ship their stock Android versions with proprietary hardware drivers, and can release little to no documentation about their devices' innards. If a piece of hardware in a phone is unknown, then this makes it impossible to implement its functionality in a fork. During the development phase, the forks can have various levels of stability and functionality. The LineageOS community maintains lists of devices that are fully functional with particular versions of LineageOS.

App repositories
Unlike with Apple's iOS and its walled garden approach, Android allows users to use more than one app repository without having to root the phone.

Google Play Store
Google Play Store is the main application market controlled by Google: entertainment media, such as books, music and rental movies go through the Play Store; if the Play Store app is used, then revenue apart from advertising can be generated there. Developers also provide revenue for Google.

Abuses in revenue generation
An early and infamous example of unethical revenue generation was an anti-virus app that went "viral", but which devoted simple source code merely to change icons, waiting, and then displaying a notification that there was no virus. The ensuing speculation had it that this particular developer wasn't much different from phone makers who depend on Android's activity-per-process and message passing/file IO communication between processes. Nevertheless, Linux's vigorous developer community utilizing the Linus's Law and its given enough eyeballs development and code review method ensures that there are no buffer overrun exploits available in any inter-process kernel functions that would underlie the Dalvik virtual machine.

Google has implemented the ratings and comments system into the Play Store, and also the possibility to report a misbehaving or suspicious app.

Other app stores and repositories
There are also separate app stores provided either by manufacturers and in bigger countries, such as Russia and China, where respectively, Google services are not in favor or completely blocked, local Internet services offer an alternative.

F-Droid is an free and open source app repository, which only contains applications with free/open source software licenses, including a client to browse and install apps. F-Droid offers some apps, like Newpipe, which are not available on the Google Play Store, either by choice or due to restrictions.