Existence is a concept.
This is a problem since it is a word that is meant to encompass the totality of human consciousness of the self, since it is the self that 'exists'.
Underneath the weak framework of conceptual reality is the idea of nothing, a void. This is where you will find the actual existence, as this is what would go on were there no language to interpret it. No-thing is without meaning. Of course something would take place, but that something would not require human interpretation.
Existence is a coming into consciousness. If you were not aware of a slug in Antarctica then it would not exist to you since it had not come into your consciousness.
One might wonder how many degrees of existence there are. The more you try and understand a concept, the more language that is required, and the more understanding that is required in order to link the concepts all together. This is an exponential complexity of our human awareness!