This Ph.D. Thesis is devoted to the derivation of cosmological constraints
by using clusters of galaxies as probes.
Clusters of galaxies provide potentially powerful means to measure
the growth of cosmic structures, as well as excellent astrophysical laboratories. As such they have played an important role in establishing the
current cosmological paradigm. On one hand, the results presented in this Thesis provide cosmological
constraints from the best X-ray surveys of distant galaxy clusters available at
present. On the other hand, the techniques developed to forecast constraints
from future survey represent a flexible tool to optimize the design of future
surveys of galaxy clusters to shed light on the content of the "Dark Sector" of
the Universe and on the nature of gravity.
