How do you define an enum class in Kotlin?

In Kotlin, you can define an enum class using the `enum` keyword. Enum classes are used to represent a fixed number of constants or values. Each constant in an enum class is an instance of the enum class itself. Here's the syntax to define an enum class in Kotlin :

enum class EnumClassName {
    CONSTANT1,
    CONSTANT2,
    CONSTANT3,
    // ...
}​

Let's break down the syntax :

* The `enum` keyword is used to indicate the declaration of an enum class.
* `EnumClassName` is the name you choose for your enum class. You can use any valid identifier as the class name.
* Inside the curly braces `{}`, you list the constant values of the enum class, separated by commas.

Here's an example of defining an enum class called `Color` with three constants: `RED`, `GREEN`, and `BLUE`:

enum class Color {
    RED,
    GREEN,
    BLUE
}​

You can use enum constants like any other value in Kotlin. For example, you can access them using dot notation (`Color.RED`, `Color.GREEN`, etc.), compare them for equality (`==`), iterate over them, and use them in switch-like expressions (when statements) to perform different actions based on the enum value.

Enums in Kotlin can also have additional properties, functions, and even implement interfaces if needed. Each enum constant can have its own set of properties and functions. Enums provide a convenient and type-safe way to define a set of related constant values and are widely used for representing a fixed set of options or states in applications.