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