Android engineering wiki
How Android actually works.
Ten notes written for engineers, not end users. The first half goes from the Linux kernel up to a rendered frame; the second half is the hands-on path every Android engineer learns. Read in order — each note builds on the one before it.
Foundations
How Android actually works under the hood — the OS, the kernel, and how an app comes to life.
01🤖 What is Android?4 minNot just an app framework — an OS, a runtime, and a set of platform services, all shipped together.AOSPLinux kernelARTBinder IPC02🐧 What is Linux?4 minThe kernel Android is built on — and the handful of kernel concepts that actually matter for app engineers.kernelprocess & UIDfile permissionssignals03🧩 How Android was built on Linux5 minSame kernel, almost nothing else the same — Bionic instead of glibc, Binder instead of pipes, ART instead of a JVM.BionicBinderLow Memory Killerwakelocks04🏗️ How Android is built4 minFrom kernel source to a signed system image — what AOSP's build actually produces.AOSPSoong / BazelDEX bytecodeAPK / AAB05🚀 How an Android app launches5 minTap the icon to first frame: Zygote, the fork, ActivityThread, and the handful of lifecycle calls in between.ZygoteforkActivityThreadmain Looper
The learning path
The hands-on topics every Android engineer learns, each backed by a runnable repo.
06🌀 Kotlin Coroutines7 minLightweight threads that make async code read top-to-bottom — and the structured-concurrency rules that keep them from leaking.suspendlaunch vs asyncdispatchersstructured concurrencyinteractive topic →07🌊 Kotlin Flow7 minReactive streams on top of coroutines — how a stream of values is produced, transformed, and collected, and what 'cold' actually means.cold flowbuilders & operatorsStateFlow / SharedFlowbackpressureinteractive topic →08🏛️ MVVM Architecture6 minUnidirectional data flow in a UI — why the View never talks to the data layer, and what the ViewModel actually is.ViewModelUiStaterepositoryunidirectional flowinteractive topic →09🗺️ The Android Engineer Roadmap6 minThe dependency-ordered map of everything an Android engineer learns — and why the order matters more than the topics.foundationlifecycleconcurrencyarchitectureinteractive topic →10☕ From Java to Kotlin5 minThe migration isn't memorising new syntax — it's unlearning boilerplate, and letting null-safety remove a whole class of bugs.data classnull-safetywhenextension functionsinteractive topic →
Full index
Every note in order, for jumping straight to a specific topic.