We present theoretical treatment and experimental data on the factors of stabilisation within emulsion systems. First a brief description of the hydrodynamic theory of thinning of emulsion films in the presence of surfactants is provided. This theory could be applied to explain the empirical Bancroft rule and some effects related to the HLB scale of surfactants. Complimentary experimental methods for investigating of model emulsions - films, drops and batch systems are described. An overview of our experimental data on the behavior of emulsions stabilised with non-ionic surfactants and proteins is provided. Attention is then turned to two recently uncovered phenomena of stabilisation of emulsion films, arising from surfactant re-distribution between the phases.