The term "antibiotic" was first proposed by Vuillemin in 1889 but was first used in the current sense by Walksman in 1941. An antibiotic is defined as a "derivative produced by the metabolism of microorganisms that possess antibacterial activity at low concentrations and is not toxic to the host." In this article, the author describes how bacterias and viruses develop resistance to antibiotics. A case study that explained the dangers of improper antibiotic treatment is also presented at the first part of the article. (Contains 2 tables.)