val and var

Kotlin has two keywords for declaring variables, val and var. The var variable is a mutable variable, that is, a variable that can be changed to another value by reassigning it. This is equivalent to declaring a variable in Java:

    var name = "kotlin" 

In addition to this, the var variable can be initialized later:

    var name: String 
    name = "kotlin" 

Variables defined with var can be reassigned, since they are mutable:

    var name = "kotlin" 
    name = "more kotlin" 

The val keyword is used to declare a read-only variable. This is equivalent to declaring a final variable in Java. A val variable must be initialized when it is created, since it cannot be changed later:

    val name = "kotlin" 

A read-only variable does not mean the instance itself is automatically immutable. The instance may still allow its member variables to be changed through functions or properties, but the variable itself cannot change its value or be reassigned to another value.