The interaction of microbes within nature, with humans and other animals makes them our friends or foes. Some of microbes are friends and some are foes, Microbes that are friendly perform some of the most important activities that make life possible on this earth, like the nitrogen fixation taking place in the soil that makes it available for the growth of the plants. Some are able to degrade complex substances into simple nutrients thus making them available for plant nutrition, some microbes are used for the making of curd, cheese and production of antibiotics and vaccines. Some activities of microbes make them our foes, like their growth in human, plant or animal body and damage to the body that is called disease. Some microbes produce chemical substances like acids that damage materials like metal pipes, fabric and wood. This called as biodeterioration. Also the microbes that are friendly may become nuisance if they get displaced from their habitats. But the usefulness of microbes outweighs the damage caused by them.