  This article discusses recent attempts to provide a deeper understanding of
the thermoreversible "gel" state of colloidal matter and to unravel the
analogies between gels at the colloidal level and gels at the molecular level,
commonly known as network-forming strong liquids. The connection between
gel-forming patchy colloids and strong liquids is provided by the limited
valence of the inter-particle interactions, i.e. by the presence of a limit in
the number of bonded nearest neighbors.
