An antimicrobial is a substance that kills or inhibits the growth of micro-organisms such as bacteria, fungi,
protozoans, etc. On the basis of mode of action, antimicrobials are classified into two broad categories as
Microbicidal that kill microbes without leaving any option for their survival and Microbistatic that cease all the
metabolic activities of microbes that are important for their survival so they are called as growth inhibitors of
microbes. The history of antimicrobials begins with the observation of Pasteur and Joubert who discovered that one
type of microbe could prevent the growth of other. That growth inhibition was due to secretion of a compound that
later got called as Antibiotic. Nowadays the term antibiotics is not confined to secretions of microbes only but also
includes all those synthetic drugs that help body to get rid of any bacterial infection. The discovery of antimicrobials
like Penicillin and Tetracycline paved way for better health of people in the world by curing diseases like
Gonorrhea, Strep throat and Pneumonia.