What existing data type categories do you know in Kotlin?

In Kotlin, the following main categories of data types exist:

• Primitive types (numbers, characters, boolean values): Int, Long, Double, Float, Char, Boolean.
• Strings: String — an immutable type for text.
• Collections:
  • Mutable (modifiable): MutableList, MutableSet, MutableMap.
  • Read-only (for reading only): List, Set, Map.
• Nullable types: any type can be declared with ?, for example, String?, to allow null values.
• User-defined classes and objects: classes, data class, sealed class, etc.
• Functional types: function types, for example, (Int, Int) -> Int.

Kotlin also supports type extensions and wrapper types, making the type system flexible and powerful.