Kotlin Academy · Lesson

val vs var: Immutability From Day One

Understand the difference between val and var and why immutability matters.

Two Ways to Declare a Variable

Kotlin has two keywords for declaring variables: val for read-only (immutable) references, and var for mutable ones. Choosing correctly matters.

val declares a reference that cannot be reassigned after initialization. Think of it like final in Java.

val name = "Kotlin"
println(name)
// name = "Java" // Error: Val cannot be reassigned