SAFT is a Helmholtz energy term that can be used in equations of state that describe the thermodynamic and phase equilibrium properties of pure fluids and fluid mixtures. SAFT was developed using statistical mechanics. SAFT models the Helmholtz free energy contribution due to association, i.e. hydrogen bonding. SAFT can be used in combination with other Helmholtz free energy terms. Other Helmholtz energy contributions consider for example Lennard-Jones interactions, covalent chain-forming bonds, and association (interactions between segments caused by, for example, hydrogen bonding). SAFT has been applied to a wide range of fluids, including supercritical fluids, polymers, liquid crystals, electrolytes, surfactant solutions, and refrigerants.