The 5 Branches of Philosophy
Reality Is Absolute
Sum Of Parts
Metaphysical vs. Man-Made
Nothing, or non-existence, is that which doesn't exist. It is not a metaphysical entity. It doesn't exist. It has no identity. It is not an object.
Non-existence is a concept that is meaningless by itself. It isn't something. It is a relational concept, gaining meaning only in comparison to another concept. Non-existence gains meaning only in comparison to existence. It is the denial of existence. The concept "nothing" is a denial of the existence of a particular entity. Both "non-existence" and "nothing" are denials of concepts, which must be accepted and understood in order to give meaning to "non-existence" or "nothing".
The important point is that "nothing" is just that: nothing. It doesn't exist. It has no identity. It's not a vacuum. It's not dark. It's not cold. It has no characteristics. As a tool of cognition, it can be useful, but doesn't exist.