The Future is what will happen in the time after the present. Its arrival is considered inevitable due to the existence of time and the laws of physics.
Due to the apparent nature of reality and the unavoidability of The Future, everything that currently exists and will exist can be categorized as either permanent, meaning that it will exist forever, or temporary, meaning that it will end.
The opposite of presentism is ‘eternalism’, which is the belief that things in the past and things yet to come exist eternally.
Another view is sometimes called the ‘growing block’ theory of time – which postulates that the past and present exist, but The Future does not.