  The nature of the dark matter in the halo of our Galaxy is still largely
unknown. The microlensing events found so far towards the Large Magellanic
Cloud suggest that at most about 20% of the halo dark matter is in the form of
MACHOs (Massive Astrophysical Compact Halo Objects). The dark matter could
also, at least partially, consist of cold molecular clouds (mainly $H_2$).
Another possibility is that WIMPs (Weakly Interacting Massive Particles) make
up the dark matter and that, due to annihilition processes, they show up
through gamma-ray emission.
