Kotlin is an open-source, statically-typed programming language that supports both object-oriented and functional programming. Kotlin provides similar syntax and concepts from other languages, including C#, Java, and Scala, among many others. Kotlin does not aim to be unique—instead, it draws inspiration from decades of language development. It exists in variants that target the JVM (Kotlin/JVM), JavaScript (Kotlin/JS), and native code (Kotlin/Native).
Kotlin is managed by the Kotlin Foundation, a group created by JetBrains and Google, that is tasked with advancing and continuing development of the language. Kotlin is officially supported by Google for Android development, meaning that Android documentation and tooling is designed with Kotlin in mind.
Certain Android APIs, like Android KTX, are Kotlin-specific, but most are written in Java and can be called from either Java or Kotlin. Kotlin’s interoperability with Java is core to its growth. It means that you can call into Java code from Kotlin and vice-versa, leveraging all of your existing Java libraries. Kotlin’s popularity results in a nicer development experience on Android, but development of the Android framework continues with both Kotlin and Java in mind.
Kotlin's interoperability with Java means that you don’t have to adopt Kotlin all at once. You can have projects with both Kotlin and Java code. For more information on adding Kotlin to an existing app, see Add Kotlin to an existing app. If you are a part of a larger team, the size of your organization and codebase may necessitate special focus. For tips and other information, see Adopt Kotlin for large teams.
If you’re looking to start from scratch with Kotlin, we offer a 30-minute crash course to help you get started with Kotlin. You can find the official Kotlin documentation at https://kotlinlang.org. For recommended books, see Books.
For Android-specific Kotlin examples, see Common Kotlin Patterns in Android.