Different types of defects have been introduced in ferrite thin films and bulk (powder) systems by implementing different methods namely swift heavy ion irradiation, impurity doping.and mechanical milling. Swift heavy ions (190 MeV Au ions and 150 MeV Ni ions) induced defects in nanocrystalline ferrite thin films arise due to formation of the latent tracks and the point defects. We have elaborately discussed the observed effects in magnetic, surface and electrical properties of ferrite thin films irradiated with SHI. The effects of point defects in impurity doping (In 3+ ions) and the effects of dislocations in mechanical milling (for different hours) have also been discussed in this paper.