What is the identity of dark matter ?

What could be dark matter and what it's identity ?

You are trying the wrong forum. There is very little agreement even among physicists about Dark Matter. There appears to be no direct evidence for the presence of something that is believed to pervade the whole Universe. One has to infer from gravitational measurements about this. Try talking to some physicists. I tried but didn’t get very far.

Dark Matter:

https://home.cern/about/physics/dark-matter 

Empirical evidence for dark matter:

https://arxiv.org/pdf/astro-ph/0608407