- Extension properties and operators. - An analogue to the ?? operator that returns null if any object in a chain of lookups is null, e.g. var furniture = house.livingroom.sofa without having to null-check every step. - Return type covariance. - typedef support, mainly to alias a pervasively used ugly generic type without needing to put a using statement in every file. More useful for value types that can't be subclassed to achieve similar ends.