Biosurfactants are surface-active biomolecules that are produced by a variety of microorganisms. They have gained biotechnologist interest for high diversity and their efficient action in comparison to synthetic emulsifiers. So, we discussed a wide array of screening method based on direct and indirect surface and interfacial tension measurements. Also, this review describes biosurfactant physicochemical properties and natural role in the environment. Also, it presents their tolerance to extreme conditions of temperature, pH and ionic strength, low toxicity and biodegradability. Functional properties like emulsification, foaming, solubilizing and membrane permeabilizing activities were also discussed along with their related application.