Introduction to Android

🗓 May 31, 2026 • ⏱ 1 min read

What is Android?

Android is an open-source operating system built on top of the Linux kernel. It runs on phones, tablets, TVs, watches and cars. As a developer, you write apps that sit on top of this system and use its building blocks to show screens, store data and talk to the internet.

The Android stack

Think of Android as a cake with layers. Your app sits on top and talks to the layers below it:

Apps — what users see (your code).
Java/Kotlin Framework APIs — ready-made tools (Activities, Views, databases).
Native libraries & Android Runtime (ART) — runs your compiled code fast.
Linux kernel — drivers, memory, security.

Languages you can use

Kotlin is the modern, recommended language. Java is still supported. Here is the classic first program in Kotlin:

fun main() {
    println("Hello, Android!")
}

Tip: Start with Kotlin. It is shorter, safer (no surprise null crashes) and is what Google uses in all new docs.