Take a look at this cheatsheet and quick reference.

It's functional - Kotlin uses many concepts from functional programming, such as lambda expressions.

Safe - Avoid entire classes of errors such as null pointer exceptions.

Concise - Drastically reduce the amount of boilerplate code you need to write.You can continue to use existing libraries in Java. 100% interoperable with Java - Kotlin and Java can co-exist in one project.Since the goal of Kotlin was for use in improving their products, it focuses very strongly on interop with Java code and the Java standard library. The language was created in response to limitations in Java which were hindering development of JetBrains' software products and after an evaluation of all other JVM languages proved unsuitable.

Kotlin is purposely built for large scale software projects to improve upon Java with a focus on readability, correctness, and developer productivity. Kotlin is a language by JetBrains, the company behind IntelliJ IDEA, which Android Studio is based on, and other developer tools.

Android studio java kotlin