What is a default parameter in Kotlin?

Default parameters allow function parameters to have pre-defined values that are used when the caller omits that argument. Example: fun greet(name: String = "World") = "Hello, $name!" can be called as greet() or greet("Kotlin"). Default parameters dramatically reduce the need for overloaded functions — a single function with defaults replaces many Java overloads. They work well with named arguments: createUser(name = "Alice", admin = true) clearly documents intent and avoids mistakes with boolean parameters.