Kotlin is the modern programming language Google officially recommends for building Android apps. It replaces Java for most new Android work, and developers love it because it does the same job with less code and fewer crashes. If you want to build Android apps — or you like Java but wish it were shorter, safer, and more pleasant — Kotlin is the language to learn.

How does Kotlin work? Kotlin runs on the Java Virtual Machine, just like Java, which means it can use every Java library ever written — and Java code and Kotlin code can live in the same project. But Kotlin adds modern features: null safety, which catches the most common Android crash before your app ever runs; data classes, which create a whole class in one line; and coroutines, which make background work like network calls simple to write. You write Kotlin in Android Studio, Google's official tool, and it compiles to an app you can run on your phone.

Kotlin is a good fit for beginners because it is designed to be readable.…