What is the purpose of Null values in programming?

The Null type in programming is used to indicate the absence of a value or a reference to an object. It allows explicitly specifying that a variable or object is uninitialized or contains no data. In Flutter (Dart), with the introduction of null safety, variables by default cannot be null, which helps prevent errors related to null dereferencing (NullPointerException). For example:

int? nullableNumber = null; // can be null
int nonNullableNumber = 5; // cannot be null

Thus, Null helps manage data state and prevent runtime errors.