How does Kotlin achieve interoperability with Java at a bytecode level?

Kotlin compiles to JVM bytecode, enabling direct Java interoperability.

Kotlin code is compiled into Java-compatible bytecode, which means both Kotlin and Java share the same runtime (JVM). Kotlin introduces metadata annotations to preserve language features like null safety, extension functions, and data classes. At runtime, Java sees Kotlin constructs as standard JVM classes. Null-safety is enforced at compile time using annotations like @NotNull and @Nullable, but Java can still bypass them, making interoperability powerful but requiring caution.