Nanoparticles are particles that have at least one dimension in a nano scale. They have properties different from their own macro scale properties. Magnetic nanoparticles are particles whose properties can be manipulated upon exposure to a magnetic field. Magnetic nanoparticles find application in material science, magnetic fluid recording, catalysis, bio-medicines, etc. There are various methods of synthesizing magnetic nanostructures, some of them are: chemical synthesis, thermal decomposition and template assisted fabrication. Template assisted fabrication has an advantage over chemical synthesis. The synthesis method defines the shape, size, magnetic property and surface chemistry of the magnetic nanoparticle. Magnetic nanoparticles can show any one of these magnetic behaviors – diamagnetism, paramagnatism, antiferromagnetism and ferromagnetism. Magnetite is a common example of a magnetic nanoparticle and it is used in many applications, due to its supermagnetic behavior. However, at the same time it is sensitive to oxidation & agglomeration, which can be prevented by various coatings.