Welcome to the very first chapter of our complete Kotlin tutorial series — just like we promised, taught in the same detailed, patient, human-teacher style as a good classroom session.
Today we’re going to answer the most important questions before writing even a single line of code:
- What is Kotlin really?
- Where did it come from?
- Why should I learn it in 2025/2026?
- How is it better (or different) than Java, Scala, Python, etc.?
- What can I actually build with Kotlin?
- How do I set up my computer so I can start coding right away?
Let’s begin!
1. What is Kotlin? (In simple human words)
Kotlin is a modern, concise, safe, and extremely fun-to-write programming language created by JetBrains (the same company that makes IntelliJ IDEA, PyCharm, WebStorm, etc.).
Officially: Kotlin is a statically-typed programming language that runs on the Java Virtual Machine (JVM) and can also be compiled to JavaScript, native binaries (via Kotlin/Native), and even WebAssembly.
But in human language: Kotlin is Java, but much nicer to write. It removes almost all the boring and annoying parts of Java while keeping 100% compatibility with every Java library ever written.
You can use Spring Boot, Hibernate, OkHttp, Retrofit, Gson, JUnit, Android SDK… literally everything that works in Java — works in Kotlin too. And usually with much less code.
2. Brief History of Kotlin
| Year | Milestone |
|---|---|
| 2010 | JetBrains starts a secret internal project called “Kotlin” |
| 2011 | First public announcement at the JVM Language Summit |
| Feb 2016 | Kotlin 1.0 released — considered production-ready |
| 2017 | Google announces official support for Kotlin on Android (huge moment!) |
| 2019 | Kotlin becomes Google’s preferred language for Android development |
| 2021 | Kotlin 1.5 → inline classes, unsigned integers, new JVM IR backend |
| 2023 | Kotlin 1.8 / 1.9 → huge improvements in multiplatform & compiler |
| 2024 | Kotlin 2.0 released — new K2 compiler (much faster), context receivers, better multiplatform support |
| 2025 | Kotlin continues to grow extremely fast — now used by Netflix, Airbnb, Pinterest, Square, Trello, Autodesk, Coursera, Atlassian… |
3. Why Kotlin? (Compared to Java, Scala, etc.)
| Feature / Aspect | Java (classic) | Kotlin | Scala | Python / JavaScript |
|---|---|---|---|---|
| Null Safety | No (NullPointerException hell) | Built-in (game changer!) | Optional (but not as nice) | No (but dynamic) |
| Code verbosity | Very high | Very low (50–70% less code) | Medium–high | Very low |
| Java interop | — | Perfect (100%) | Good but not perfect | Poor |
| Performance | Excellent | Same as Java | Same as Java | Much slower |
| Learning curve | Medium | Easy if you know Java | Steep | Very easy |
| Modern features | Slow to adopt | Lambdas, extensions, coroutines, DSLs… | Many (but complex) | Many (dynamic) |
| Android support | Official but painful | First-class citizen | Not really | Not possible |
| Multiplatform (mobile, web, desktop, server, native) | Only JVM | Excellent (KMP) | Limited | Limited |
Bottom line: Kotlin gives you:
- All the power and ecosystem of Java
- Much less boilerplate
- Much better safety (null safety, immutability by default)
- Modern language features without the complexity of Scala
- The best developer experience on the JVM today
4. Real-World Use Cases of Kotlin (2025–2026)
| Domain | Popular Frameworks / Tools | Companies / Apps using Kotlin heavily |
|---|---|---|
| Android | Jetpack Compose, Kotlin Coroutines, Koin/Dagger-Hilt, Retrofit, Room, Navigation Compose | Google, Airbnb, Pinterest, Trello, Evernote, Square, Duolingo, Netflix |
| Backend / Server | Spring Boot 3, Ktor, Micronaut, Quarkus, Exposed, Ktorm | Netflix, Pinterest, Atlassian, Autodesk, JetBrains, Coursera |
| Kotlin Multiplatform (KMP) | Shared business logic + UI (Compose Multiplatform) | Netflix (mobile + TV), Autodesk, Cash App, McDonald’s, 9GAG |
| Desktop | Jetpack Compose for Desktop, TornadoFX | JetBrains (IntelliJ plugins), some internal tools |
| Scripting | .kts files, Gradle build scripts | Almost all modern Gradle projects |
| Data Science / Notebooks | Kotlin Dataframe, Kotlin for Jupyter | Growing fast in data teams |
| Game Development | LibGDX (Kotlin-first now) | Many indie games |
5. Setting Up Your Kotlin Environment (Step-by-Step)
You have three main ways to start writing Kotlin today — I recommend starting with Option 1 or Option 2.
Option 1: IntelliJ IDEA (Recommended – Best Experience)
- Download IntelliJ IDEA Community Edition (completely free) → https://www.jetbrains.com/idea/download/
- Install JDK 17 or 21 (LTS versions – highly recommended)
- Easiest: Let IntelliJ download it for you during project creation
- Or manually: https://adoptium.net/ (Eclipse Temurin) or https://www.oracle.com/java/technologies/downloads/
- Create your first Kotlin project
- Open IntelliJ IDEA
- Click New Project
- Select Kotlin → JVM | IDEA
- Give it a name (e.g., KotlinPlayground)
- Choose JDK 17 or 21
- Click Create
- Write your first program (we’ll do this in Chapter 2)
Option 2: Kotlin Playground (Zero Installation – Online)
→ https://play.kotlinlang.org
- Just open the link in your browser
- You can write, run, and share Kotlin code instantly
- Perfect for learning Chapters 1–15
- (Later you’ll want a local IDE for bigger projects)
Option 3: Command-Line Only (For Terminal Lovers)
- Install JDK 17/21
- Download Kotlin compiler: https://kotlinlang.org/docs/command-line.html or via SDKMAN! (recommended for Mac/Linux):
|
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curl -s "https://get.sdkman.io" | bash sdk install kotlin |
- Create a file Hello.kt
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fun main() { println("Hello, Kotlin!") } |
- Compile & run:
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kotlinc Hello.kt -include-runtime -d Hello.jar java -jar Hello.jar |
or simply:
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kotlinc -script Hello.kts |
Summary – Why You Should Be Excited About Kotlin
- Null safety → goodbye NullPointerException
- Concise & beautiful code
- Full Java compatibility → huge ecosystem
- Coroutines → easy asynchronous programming
- Multiplatform → write once, run on Android, iOS, Desktop, Web, Server…
- JetBrains backing → best tooling in the world (IntelliJ IDEA)
