The field may have a default value or remain uninitialized.
Forgetting to initialize a field can lead to unexpected behavior, as the field might default to a value like null or zero, which might not be valid for your application. For instance, if a ShoppingCart class forgets to initialize the list of items, it might start with a null reference, causing errors when trying to add items.
Additional Notes
What happens if you forget to initialize a field in a constructor?