The high-pressure phase equilibria of fluids  has important consequences, ranging from practical applications to frontier sciences. A well-known example of the former is the removal of caffeine from coffee via supercritical extraction whereas modelling the chemical behavior of Saturn and Jupiter is a more exotic application. The diversity of phenomena expands as the number of components in increases. So-called â??islands of immiscibilityâ? are observed when three of more component are involved resulting from the complex interplay of mixing and de-mixing processes. The phenomena are ultimately governed by fundamental differences in the interactions between molecules and experimental phase behavior data have provided the impetus for both the development of theory  and molecular simulation  techniques. This work highlights progress in understanding phase equilibria at high prressures, emphasising new developments  that may challenge our understanding of phenomena at high pressures.
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