Inhomogeneous cosmological models: exact solutions and their
  applications
  Recently, inhomogeneous generalisations of the
Friedmann-Lemaitre-Robertson-Walker cosmological models have gained interest in
the astrophysical community and are more often employed to study cosmological
phenomena. However, in many papers the inhomogeneous cosmological models are
treated as an alternative to the FLRW models. In fact, they are not an
alternative, but an exact perturbation of the latter, and are gradually
becoming a necessity in modern cosmology. The assumption of homogeneity is just
a first approximation introduced to simplify equations. So far this assumption
is commonly believed to have worked well, but future and more precise
observations will not be properly analysed unless inhomogeneities are taken
into account. This paper reviews recent developments in the field and shows the
importance of an inhomogeneous framework in the analysis of cosmological
observations.
