I review some important aspects of the structural and statistical properties
of the nearby X-ray galaxy cluster population, discussing the new constraints
on mass profiles, the mass-temperature relation, and the entropy of the
intracluster medium which have become available from recent X-ray observations.Comment: 11 pages, 4 figures. Invited review to appear in the proceedings of
the XLIst Rencontres de Moriond, XXVIth Astrophysics Moriond Meeting: "From
dark halos to light", Eds. L.Tresse, S. Maurogordato and J. Tran Thanh Van.
Typos corrected, added reference
