Type inference is a feature in Kotlin that allows the compiler to automatically determine the type of a variable or expression based on its context and assigned value. In other words, the compiler can infer the type without the need for explicit type annotations.

When a variable is declared without specifying its type, the compiler analyzes the assigned value and infers the most specific type that matches the value. This reduces the need for developers to explicitly declare the type, making the code more concise and readable.

Here's an example to illustrate type inference in Kotlin :

val number = 42 // The type of 'number' is inferred as Int
val name = "John" // The type of 'name' is inferred as String
val pi = 3.14 // The type of 'pi' is inferred as Double
val flag = true // The type of 'flag' is inferred as Boolean​

In the above code snippet, the types of the variables (`number`, `name`, `pi`, and `flag`) are inferred based on the assigned values. The compiler analyzes the values (`42`, `"John"`, `3.14`, and `true`) and deduces the most appropriate type.

Type inference in Kotlin is smart and takes into account the available information and context. It works not only for variable declarations but also for function return types and other expressions.

It's important to note that while type inference is powerful and convenient, explicit type annotations can still be used when necessary or to improve code readability. Additionally, type inference may not always be possible if the assigned value is ambiguous or if the type cannot be determined from the context.