What is the reason for returning the add method of boolean type?

The add method in Java collections, such as ArrayList, returns a boolean value to indicate whether the operation of adding an element was successful. This is useful, for example, in collections where adding may not occur (such as in Set, where duplicates are not allowed). In the case of ArrayList, the method always returns true since adding an element is always successful, but the return value allows for a unified interface across different collections.