Kotlin is a modern, statically-typed programming language developed by JetBrains, designed to be fully interoperable with Java. It runs on the Java Virtual Machine (JVM) and is primarily used for developing Android applications, though it can also be used for server-side, web, and desktop development. Kotlin offers features like null safety, concise syntax, and functional programming capabilities, making it a more expressive and error-resistant alternative to Java. It is officially supported by Google for Android development, and its seamless integration with Java makes it a popular choice for developers looking to modernize their codebases.