Figure 1: The distribution of dark matter obtained from a large numerical simulation. Note how the dark matter is clustered into dark matter halos, which are connected by a large filamentary network. It is form simulations like these that astrophysicists have obtained a detailed understanding of the abundance and clustering of dark matter halos. This particular simulation is performed by the Virgo consortium, including scientists from the Max-Planck Institute for Astrophysics (see Jenkins et al. 1998, Astophysical Journal, 499, 20-40)

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Taken from the Max Planck Institute for Astrophysics.