In most cases the deformations and displacements are small in comparison with the dimensions of a body. However, some structures such as springs and membranes have large displacements corresponding to small deformations. Deformation modifies the colloidal interactions like electrostatic, van der Waals, steric, depletion, hydration, etc. It also gives rise to additional contribution due to the deformation of the interface itself, which is not present in solid dispersions. This contribution is due to the extension of the droplet surface and/or change of the local curvature upon deformation. where γ0 is the interfacial tension of a spherical, undeformed droplet and is the Gibbs elasticity of the surfactant monolayer stabilizing the droplet. Often the second term could be ignored when compared to the first one, and this is the case for most emulsion systems. For systems with extremely low interfacial tension, however, the Gibbs elasticity term becomes dominant. Such systems often tend to form microemulsions in which the bending rigidity of the interface also becomes important,