Metaphysics examines the most general features of reality, existence, objects, and properties; concerned with explaining the fundamental nature of being and the world that encompasses it.;
Cosmology – the study of the nature and origins of the universe.
Ontology – philosophical study of the nature of being, becoming, existence, or reality, as well as the basic categories of being and their relations.
Meta-ontology – study of the ontological foundations of ontology itself.
Philosophy of space and time – branch of philosophy concerned with the issues surrounding the ontology, epistemology, and character of space and time.