Dark matter1

Dark matter is a type of matter hypothesized in astronomy and cosmology to account for a large part of the mass that appears to be missing from the universe. Dark matter cannot be seen directly with telescopes; evidently it neither emits nor absorbs light or other electromagnetic radiation at any significant level. Dark Matter is not exactly balck hole. The composition of the constituents of cold dark matter is currently unknown. It could be group of black holes, dwarfs or some new particle.