Since Android Studio 3.0 (released in October 2017), Kotlin is fully supported by Google for use in application programming for their Android operating system,  and is embedded directly into the package. That IDE’s installation replaces the standard Java compiler. Android compiler Kotlin allows users to choose between targeting bytecode code compatible with Java 6, or Java 8.
In July 2011, JetBrains introduced Project Kotlin, a new language for the JVM that has been developed for a year.  Leader JetBrains Dmitry Jemerov said that most languages do not have the features they seek, except Scala. However, he pointed out that Scala’s too slow compile time is an obvious drawback. One of Kotlin’s mentioned goals is to compile as fast as Java. In February 2012, JetBrains opened the source of the project under the Apache license 2.
Its name comes from Kotlin Island, near St. Petersburg. Andrey Breslav mentioned that the group decided to choose the island name as Java is named after the Indonesian island of Java (although the Java programming language is probably named after a type of coffee).
JetBrains hopes that the new language will boost IntelliJ IDEA sales.
Kotlin v1.0 was released on February 15, 2016.  This is considered the first stable official version and JetBrains has committed to long-term backward compatibility since this version.
At the Google I / O conference 2017, Google announced first-class support for Kotlin on Android.
Kotlin v1.3 was released on October 29, 2018, with coroutine API for asynchronous programming.
Development team leader Andrey Breslav said that Kotlin was designed to be a strong industrial-oriented language, and a “better language” Java, but still fully compatible with Java code, for allow companies to transition gradually from Java to Kotlin. 
A semicolon is an option to end a statement; In most cases, a newline is enough for the compiler to understand that the statement has ended.
How to declare the variable Kotlin and the parameter list has the data type followed by the variable name (with a delimiter), similar to Pascal.
The variable in Kotlin can be immutable, by declaring with the keyword val, or mutable, by declaring it with the var keyword. 
The members of the default class are public (public), and the classes themselves are by default “final”, meaning that creating a derived class is disabled unless the base class is declared with the keyword open.
In addition to classes and methods (called member functions in Kotlin) of object-oriented programming, Kotlin also supports procedural programming with the use of functions.