During hydrocarbon production and reservoir depletion, the produced fluid is subjected to several phase behavior changes. Understanding these changes is essential because of their impact on reservoir reserve and development strategies, particularly for EOR processes. Both laboratory experiments and correlations can be used to obtain pressure-volume-temperature (PVT) data that can be later used for a best representation of a certain reservoir rocks and fluids characteristics. With more challenges in characterizing reservoir fluids especially in tight systems, PVT and fluid characterization technologies have been developed. Some of the challenges include near-critical gas condensate and volatile oil, unconventional, sour gasses, high pressure high temperature gas/oil, bitumen, and heavy oils. This area includes several aspects such as black-oil PVT properties, laboratory techniques, correlation data, fluid sampling, equation of state (EOS), regression techniques for tuning EOS, slim tube simulations, unconventional phase behavior, simulation of experiments, and PVT for simulation.