Introduction

Why Kotlin?

Kotlin is a modern, statically typed language that runs on the JVM, and is the preferred language for Android development. Created by JetBrains and adopted by Google, it combines the safety of static typing with the conciseness of functional programming.

  • Concise syntax — Kotlin eliminates boilerplate. Data classes, lambdas, and extension functions let you do in 5 lines what Java does in 50.
  • Null safety — the type system distinguishes nullable from non-nullable types, eliminating entire classes of NullPointerExceptions at compile time.
  • Functional programming — first-class functions, lambdas, and a rich collections API make it easy to write expressive, composable code.
  • Interoperable — Kotlin runs on the JVM and is 100% interoperable with Java. Use any Java library from Kotlin, and vice versa.
  • Multiplatform — Kotlin can target the JVM, JavaScript, and native platforms (iOS, macOS, Linux) from a single codebase.

The Story

Kotlin was created by JetBrains, the company behind IntelliJ IDEA and other developer tools. Version 1.0 was released in 2016. In 2017, Google announced first-class support for Kotlin on Android, and in 2019 declared it the preferred language for Android development.

The name comes from Kotlin Island, near Saint Petersburg, Russia — following the tradition of naming languages after islands (Java, Ceylon).

What You Will Learn

This course has 15 lessons organized into 5 chapters:

  1. Basics — Hello World, variables, strings, and numbers.
  2. Control Flow — Conditionals (if/else), when expressions, and loops.
  3. Functions — Function declarations, default parameters, and lambdas.
  4. Collections — Lists, list operations (map, filter, fold), and maps.
  5. OOP & Data — Data classes and higher-order functions.

All code runs entirely in your browser via a JavaScript transpiler — no installation required.

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