Android

Android is built on the Linux kernel, and its core is open source as the Android Open Source Project (AOSP). Most phones sold outside China also carry Google Mobile Services, the proprietary layer that includes Google Play, Play services, Maps and push messaging through Firebase Cloud Messaging. Apps are written in Kotlin (or Java) against the Android SDK and run on the Android Runtime (ART). Publishing on Google Play costs a one-time $25.

The variety is both the strength and the challenge: thousands of device models, screen sizes and Android versions, with manufacturers adding their own skins and battery rules. Apps can come from Google Play, other stores such as Samsung's Galaxy Store, or direct downloads (sideloading). From 30 September 2026 Google starts requiring apps on certified devices to be registered by verified developers, beginning with installs from major stores in Brazil, Indonesia, Singapore and Thailand and extending to all apps worldwide in 2027.