Kotlin is a modern programming language developed by JetBrains and officially supported by Google for Android development. It is designed to be fully interoperable with Java and addresses many of the pitfalls of Java, such as verbosity and null pointer exceptions. Kotlin introduces features such as null safety, extension functions, and infix notation that enable concise and expressive code designs. With its adoption on the Android platform, Kotlin has rapidly become a favorite for mobile developers. Additionally, Kotlin is highly effective for server-side development, particularly when used with the Spring Framework.