A ferrofluid (from the Latin ferrum, meaning iron) is a liquid which becomes strongly polarised in the presence of a magnetic field. It is a colloidal mixture comprising extremely small magnetic particles suspended in a synthetic oil. The particles are coated with a a soap or detergent to prevent them from clumping together.Ferrofluids are composed of nanoscale ferromagnetic particles suspended in a carrier fluid, usually an organic solvent or water. The ferromagnetic nano-particles are coated with a surfactant to prevent their agglomeration (due to van der Waals and magnetic forces)