An antimicrobial drug is an agent that either stops the growth of microorganisms or kills them. Antimicrobial medicines can be assembled by how they act basically against the organism. For example, antifungals are used against fungi, and antibiotics are used against bacteria. Classification of them can be made according to their function. Agents that merely inhibit their growth are called bacteriostatic agents, while agents that kill microbes are microbicides. The use of antimicrobial medicines to prevent infection is known as antimicrobial prophylaxis, while the use of antimicrobial medicines to treat infection is known as antimicrobial chemotherapy.