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Cosmography represents an important branch of cosmology which aims to describe the universe without the need of postulating a priori any particular cosmological model. All quantities of interest are expanded as a Taylor series around here and now, providing in principle, a way of directly matching with cosmological data. In this way, cosmography can be regarded a model-independent technique, able to fix cosmic bounds, although several issues limit its use in various model reconstructions. The main purpose of this review is to focus on the key features of cosmography, emphasizing both the strategy for obtaining the observable cosmographic series and pointing out any drawbacks which might plague the standard cosmographic treatment. In doing so, we relate cosmography to the most relevant cosmological quantities and to several dark energy models. We also investigate whether cosmography is able to provide information about the form of the cosmological expansion history, discussing how to reproduce the dark fluid from the cosmographic sound speed. Following this, we discuss limits on cosmographic priors and focus on how to experimentally treat cosmographic expansions. Finally, we present some of the latest developments of the cosmographic method, reviewing the use of rational approximations, based on cosmographic Padé polynomials. Future prospects leading to more accurate cosmographic results, able to better reproduce the expansion history of the universe, are also discussed in detail. [ABSTRACT FROM AUTHOR]

We investigate cosmological models with a linear inhomogeneous time-dependent equation-of-state (EoS) for the dark energy, coupled with dark matter, leading to a bounce cosmology. Equivalent descriptions in terms of the EoS parameters for an ex-ponential, a power-law, or a double exponential form of the scale factor a is obtained. The stability of the solutions is explored, by considering small perturbations around the critical points for the bounce in the early and in the late-time universe. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the role of wet dark fluid (WDF) in Kantowski-Sachs space-time in the general theory of relativity. In this theory, we solved the field equations for the case where ρWDF = -2pWDF . Various physical and geometrical properties of the model are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, we have constructed a five dimensional LRS Bianchi type I cosmological model with wet dark fluid (WDF) in general relativity with the matter field described as bulk viscosity. It is found that in presence of bulk viscosity an inflationary effective stiff fluid cosmological model is obtained, whereas in absence of bulk viscosity the wet dark fluid degenerate to stiff fluid. Some physical and geometrical properties of the model are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, we test the spherical collapse of a unified dark fluid (UDF) which has constant adiabatic sound speed. By choosing the different values of model parameters B and α, we show the non-linear collapse for UDF and baryons which are considered for their formation of the large scale structure of our Universe. The analyzed results show that larger values of α and B make the structure formation faster and earlier. [ABSTRACT FROM AUTHOR]