Bacteriocins are antimicrobial peptides produced by bacteria that inhibit the growth of similar or closely related bacterial strains. They serve as a defense mechanism, helping bacteria compete for resources and establish dominance in their environment. Bacteriocins can be effective against pathogenic bacteria, making them of interest in food preservation and medical applications. These substances are typically classified based on their structure and the bacteria that produce them. Some well-known examples include nisin, produced by Lactococcus lactis, which is used as a food preservative, and lantibiotics, which have potential therapeutic uses against antibiotic-resistant infections.