Kotlin can run on the JVM and, Kotlin-on-the-JVM needs Java to even bootstrap. Also it seems that most of the interest for Kotlin comes from the JVM community

Kotlin can run on the JVM and, Kotlin-on-the-JVM needs Java to even bootstrap. Also it seems that most of the interest for Kotlin comes from the JVM community and this aspect of the language. That is certainly the case for Android programmers any how. Backend JVM application server programmers use it as well. However Kotlin can be targeted to other platforms as well. Kotlin can target JavaScript ( https://kotlinlang.org/docs/reference/js-overview.html https://kotlinlang.org/docs/reference/js-overview.html ). Also the Kotlin compiler has a LLVM based backend which can compile native binaries, without use of any VM ( https://kotlinlang.org/docs/reference/native-overview.html https://kotlinlang.org/docs/reference/native-overview.html ). My main non-JVM use of Kotlin is that when I want to use some arcane aspect of Kotlin, which I may not be too familiar with, I might write and test a small toy function on the command line using it and then copying it over to a big Android Kotlin project, as opposed to trying to work out how to use the arcane feature in the middle of a big Android project.