What is the buildList function in Kotlin?

buildList (along with buildMap and buildSet) creates an immutable collection using a builder DSL block. Inside the block, you use a MutableList to add elements, and the result is a read-only List. Example: val items = buildList { add("first"); addAll(fetchItems()); if (hasExtra) add("extra") }. This is cleaner than the alternative of creating a mutableListOf(), populating it with logic, then calling .toList(). The intent (building an immutable list) is immediately clear from the call site, and you cannot accidentally forget the .toList() conversion.