What is "kotlin"
Kotlin is a statically typed programming language developed by Jetbrains. It supports bytecode JVM and Javascript as build targets. Kotlin overcome well-known Java limitations while maintaining a reasonable build speed and user-friendly interface with tools.
Set of tools available: Intellij Idea / Plugin for Android Studio (code highlighting, compilation, self-comppletion and Refactoring), Eclipse Plugin, build plugins for Ant, Maven and Gradle, Extensions for Android.
Links Úteis
Text adapted from tag on Stack Overflow in English.