All too often, people assume that bacteria are bad and always bad. It is not well known that only a very small percentage of bacteria are harmful to humans. The rest of bacteria are either completely harmless to people or beneficial. Bacteria live inside humans in a mutualistic relationship. The bacteria and the person both benefit. In fact, about 1% to 3% of a person's overall body mass is made up of bacteria. This means that a 100 pound person has a bit more than 1 pound of bacteria inside the body. These bacteria have various uses within the body, and helping the digestive process is a common example. Bacteria are also integral in producing various foods. Sauerkraut, sour cream, yogurt, buttermilk, pickles, and vinegar are all produced with the help of bacteria. Bacteria have also entered the manufacturing world, and they are useful for producing various drugs through genetic engineering. In nature, bacteria are also involved with nitrogen fixation and decomposition.