Are you confused a little about dark matter? I know I have been for several decades, waiting for science to finally figure out what it is. I just finished a new book which helps to clarify the current understanding. The book is titled “Dark Matter and the Dinosaurs” by Lisa Randall. It’s available in the Hennepin county library system. You will need to reserve it, since it is a popular book.
The author does a good job of reviewing why we assume there is such a thing as dark matter and shows how it fits in with observations such as gravitational lensing. It also presents her and her colleagues concept of a denser dark matter disk within the galactic plane of the Milky Way. It is this disk that may have perturbed an Oort cloud comet to enter the inner solar system and smash into the earth and wipe out the dinosaurs.
All in all, it is a good read and brought me up to date on dark matter. However, I’m not sure science will figure out exactly what it is and not just how it affects the cosmos; at least in my lifetime.