#Types Overview

Last modified: 01 April 2025

In Kotlin, everything is an object in the sense that you can call member functions and properties on any variable. While certain types have an optimized internal representation as primitive values at runtime (such as numbers, characters, and booleans), they appear and behave like regular classes to you.

This section describes the basic types used in Kotlin:

• Numbers (and their unsigned counterparts)
• Booleans
• Characters
• Strings
• Arrays

---

#Additional Kotlin Types

To learn about other specific Kotlin types, look through the Kotlin API reference:

• Any: The root of the Kotlin class hierarchy. Every class in Kotlin has Any as a superclass.
• Nothing: A type that has no values. It represents a value that never exists (e.g., a function that always throws an exception).
• Unit: The type with only one value—the Unit object. This corresponds to the void type in Java.