  Gels are low-packing arrested states of matter which are able to support
stress. On cooling, limited valence colloidal particles form open networks
stabilized by the progressive increase of the interparticle bond lifetime.
These gels, named equilibrium gels, are the focus of this review article.
Differently from other types of colloidal gels, equilibrium gels do not require
an underlying phase separation to form. Oppositely, they form in a region of
densities deprived of thermodynamic instabilities. Limited valence equilibrium
gels neither coarsen nor age with time.
